The Supermassive Podcast - 45: Uranus the Oddball

Episode Date: September 29, 2023

Izzie and Dr Becky have done episodes on Mars, gas giants, Saturn and Jupiter individually, so it’s about time that Uranus gets its own episode. And just so we're clear, it's UranUs, not UrAnus.  Professor Leigh Fletcher from the University of Leicester takes the team through the basics. Plus, Izzie pays a visit to the Royal Astronomical Society’s archive to see the Herschels' notebooks from when the planet was discovered.  Recommends  Late Prom 15: Moon and Stars https://www.bbc.co.uk/events/en8fbp Public Service Broadcasting - The Race for Space - https://open.spotify.com/album/4ZaAM16hw3xpp680FJahJJ?autoplay=true Our next main episode is a Q&A, so please send your questions to [e-mail], tweet @RoyalAstroSoc or message us on Insta @SupermassivePod

Uranus. Uranus, Uranus, Uranus. It's an intriguing example of an ice giant world. We know that it has at least 27 moons. It might even be diamondbergs floating around. It might not be the flashiest, but it definitely sounds chaotic. Yeah. Hello, welcome to the Supermassive podcast from the Royal Astronomical Society with me,

science journalist Izzy Clark and astrophysicist Dr Becky Smethurst. Now we've done a few planetary episodes before, you know, we've done Mars, we've done the gas giants, we've given Saturn and Jupiter their own episode. So it's about time that Uranus gets its own as well. Yeah, it has been a little bit too long i think uranus always just gets forgotten about you're like sorry about that yeah it's just like yeah jupiter saturn oh neptune's cool like what the gas giants like uranus in the background like hey guys so coming up professor lee fletcher from the university of leicester takes us through the basics plus i pay a visit to the Royal Astronomical Society's archive to see William Herschel's notebooks from when he discovered the planets.

And as always, Dr. Robert Massey, the Deputy Director of the Royal Astronomical Society is here. So, Robert, what is Uranus like as a planet? You know, when it's waving to us to be like, hey, come and have a look at me. What's it like? Yeah, overlooked by some of us, I guess. So yeah, look, it's an example,

an intriguing example of an ice giant world. So gas giant, but further from the sun, colder, smaller, but still quite big. It's the third largest planet after Jupiter and Saturn. And it was the first planet discovered with a telescope because all the other planets from Saturn inwards are fairly easy to see with the naked eye. Mercury is a bit of a challenge,

but there are certain times of the year when it's obvious. So we can basically assume that all of these discoveries are prehistoric, that as soon as Homo sapiens emerged or even an hominin ancestor, we were able to see the planets. But Uranus was found by William Herschel, the founding president of the Royal Astronomical Society, right back in 1781 using a small telescope in his back garden in Bath with the assistance of his sister Caroline and it's barely visible to the naked eye if you know

exactly where to look it takes 84 years to go around the sun and when it was found it's twice as far away as Saturn so it doubled the size of the solar system so immediately it sort of gave us a new sense of perspective and scale and then the other wacky well one of the many wacky things about it is that he also then six years later found the moons titania and oberon with a bigger telescope and he found that it had an odd tilt because you see them going around the planet and you realize that's telling you about the tilt of the planet and it's basically knocked over on its side so it has winters that last decades at each pole it's got an atmosphere hydrogen helium and methane not not vastly different from the sun albeit a lot colder probably a solid core underneath and a water

ammonia ocean so it's really quite exotic even if we often shamefully forget about it a bit thinking of the more glamorous planets like saturn dr becky oh i also love as well have you seen this thing that's gone viral this week that's like how often do you think about the roman empire and i'm just like we like literally all the time because of like the planet's names like jupiter saturn uranus neptune how can you not think about the roman empire when they're literally like right in front of you it's all i think but yeah very exotic uranus and we're going to talk more about it as we go on so cheers robert we're going to catch up with you later in the show for some more stargazing. Okay, so that's a brief, a very brief introduction to Uranus. But will we ever send a spacecraft there? And what else do we know about this strange planet? Well, I spoke with Lee Fletcher, Professor of Planetary Science at the University of Leicester to find out.

So Uranus is the seventh planet out from the sun. It's orbiting there twice as far away as the planet Saturn. It's a bizarre world, a world we like to think of as a world of extremes. It's tilted over onto its side, so it kind of rolls around the solar system on its side over the course of 84 years around the sun. And as it's doing so, it's subjected to the most extreme seasons of anywhere in our solar system, with one of its poles spending 40 continuous years in winter darkness, followed by 40 years in summer sunshine. And of course, that strange axial tilt has profound consequences for its atmosphere, for its magnetosphere, for its collection of icy moons and for its delicate ring system as well. So it's a fascinating environment, not least because it's somewhere we want to go and explore, but also because it tests all of our ideas about what makes a planet, how do planets work and what are they made of?

It tests all of those ideas to the absolute extremes. Okay, so I need to jump right in here. Why is it on its side? Do we know why Uranus is tilted on its side? That's a great question. Now, we have plenty of ideas for why that tilt might have occurred but it's quite clear Uranus is the oddball of the solar system right nowhere else do we see a tilt quite that enormous Saturn and Neptune and Earth they all have axial tilts which are quite sensible 20 or 30 degrees so we have spring summer autumn and winter but Uranus is clearly standing out there. Now, I think the best idea is that someday in its distant past, and you're talking billions of years ago, shortly after the planet

first formed, a gargantuan collision bowled it over onto its side. Maybe another Uranus or Neptune sized world actually collided with the forming Uranus about four and a half billion years ago. And what you're seeing today is the consequences of that cataclysmic event. It clearly happened nowhere else in our solar system to quite that extremes. And it leaves us with a world today that's quite unlike any others. Okay. And so if we look at its size, how big is Uranus and what's it made of? It's an ice giant, that is something that we do know. Yeah, so I think the best thing to do is to try and compare it to some of the smaller terrestrial worlds that we have in the inner solar system. And also those large gas giants, Jupiter and Saturn.

Jupiter and Saturn. So Uranus and Neptune, because they're both similar objects in terms of size and composition, are both about four times wider in terms of radius than planet Earth. So four times the size of our own planet, but still rather small compared to somewhere like Jupiter and Saturn, which are absolutely enormous. Now, all four of those gas giant planets are primarily made of hydrogen and helium. And those were the simplest molecules that were out there at the birth of our solar system that could accrete or fall onto the forming planets around the sun. Now, Jupiter had the opportunity to gobble up all of that hydrogen and helium and just keep growing and growing and growing until it was massive, extremely large in size. And obviously today, the largest planet in the solar system. So the question then is, well, why didn't poor Uranus and Neptune grow to a similar size as Jupiter?

Maybe it didn't have quite as long to do it, or maybe it just didn't have access to quite as much hydrogen and helium. So these are giant planets that started to grow, but didn't quite manage to get to the same size as something like Jupiter. So the worlds we see today are still primarily made of hydrogen and helium, but they have less hydrogen and helium than Jupiter and Saturn, which means all of the other stuff that makes them up, and I'm talking about things like methane, like water, like ammonia, like hydrogen sulfide, they appear to be vastly enriched on the ice giants than they do on the gas giants. And that's kind of why we call them ice giants today. We're not saying they're made of ice, okay? That's the first confusing thing about Uranus and Neptune. They are

not made primarily of ice, but they did presumably accrete much more ice when they were first forming and all of that material is now vaporized or in a fluid form within the atmospheres and the interiors that we see. Okay and what about its ring system? We did an episode a few months ago on Saturn and I don't really think people think about Uranus and its rings as much as people equate it to Saturn and its rings. So what are they made up of? How big are they? How many are there? So those rings of Uranus, amazingly, were only detected back in the 1970s by looking at... Oh, wow. So that's really recent in the grand scheme of space. Compared to something like Saturn, when Christian Huygens was looking and saw the

rings of Saturn 400 odd years ago. This is very recent. Then back in the 80s, the fantastic Voyager 2 mission sailed on past Uranus and got a good glimpse at the rings of Uranus for the first time. Now, don't go away with the impression that Uranus has the same kind of gorgeous rings as Saturn, but it does have lots of very narrow, dusty rings surrounding the planet that are presumably made primarily of water ice still, but they appear to be coated in some kind of rocky, dusty material that makes them really dark. And the rings of Saturn, they're nicely held together by the delicate gravitational dance of all of the moons that are surrounding Saturn.

And you might think that that's a common feature of gravity and rings throughout the solar system. But to the best of our knowledge right now, those narrow, dusty rings of Uranus don't appear to be connected to any resonances associated with the satellites. So that's a bit of a head scratcher, a bit of a mystery. And one of the key things we want to try and do in the future is understand what is keeping those rings confined? How old are they? What are they made of? And I think these are all questions that the only way we'll answer them is one day by having a future mission out to Uranus. Yes, well, that's something I want to get onto in a moment, but let's bring it back a bit first. So how have we been able to study Uranus so far?

Because I feel like, as we touched on earlier, Voyager 2 is the only spacecraft that has flown by Uranus. That's correct, right? You're absolutely right. I mean, and Voyager 2, when it flew past Uranus, I remember talking to right? You're absolutely right. I mean, and Voyager 2, when it flew past Uranus, I remember talking to some of the scientists that were involved in that back in the 80s. And after they'd seen the glory of Jupiter and all this glorious things on Saturn and its rings, they got to Uranus and all they see is a big pale blue orb floating there in the darkness. No storms, or they counted about 10 cloud features. Now, compare that to what you're familiar with when you look at the planet Jupiter, for example.

It's just an amazing difference. And since the days of Voyager 2, of course, we haven't had another mission going out in that direction, certainly not one that could fly by Uranus. Well, is anyone at any of the space agencies going to change that can we cross our fingers and hope for a mission to Uranus anytime soon well I may have some good news for you and for your listeners okay so we recognize now it's almost been half a century since we actually got our close-up views of Uranus. And so it's time to send a robotic spacecraft back out to the outer solar system. Now, the US space program, NASA, they have said that a flagship class mission, that's a mission that's going to cost several

billion US dollars, is now their top priority for the exploration of the solar system in the coming decade. And this is tremendous news because it's reinforcing what we scientists have been shouting and screaming about for quite some time, is that this is a fascinating place to go and explore and really is the next step in our exploration of the solar system. After the amazing Cassini mission did all of its work at Saturn. Of course, the Juno and Galileo missions doing all their work at Jupiter. And now we want something that is the equivalent out there in orbit around Uranus and actually dropping a little atmospheric probe into the atmosphere of Uranus as well, which would be an amazing opportunity. Now, we have a planetary alignment coming up in the early 2030s. Jupiter is basically in the right place in the solar system to give us the extra energy we need to slingshot us out of

the solar system towards Uranus. And what that means in real terms is that you can take more with you. You can take better equipment, you can take bigger spacecraft and better probes with you if you make the most of that gravity assist. But the clock is ticking. By the mid-2030s, Jupiter's starting to wander away from where it needs to be to make the most of this gravity assist. There's still ways to get there, but you can't take quite as much with you. So I think the community and our space agencies now have a ticking clock and we want to make sure that we are ready to make the absolute most of that planetary alignment because unfortunately they only come round once every 12 or 13 years or so. So if we don't do it now, we might be back having the same conversation

in 15 years time and still waiting for that mission. So we're hopeful NASA and ESA can get their budgetary heads together and finally give us the opportunity to get out to planet number seven. Oh, fingers crossed for that mission. Come on, it's about time we did one. We need it.

That was Lee Fletcher from the University of Leicester. Okay, so Becky, Lee briefly mentioned Uranus's moons there. So how many are there and do we know what they're like? So we know that it has at least 27 moons. You know, Uranus is pretty far away. It's pretty faint in itself and its moons are very faint too. It's very hard to spot. Plus, you know, there's been no missions there since Voyager flew past it so you know it's not like we've had Cassini around Saturn which discovered loads of moons and then

you know all that kind of stuff so that number would probably go up if we could send a mission to it fun fact you know how like the IAU has like strict naming rules for certain things yeah um so like craters on mars have to be named after like generals and all this kind of stuff you're like war generals um the moons of uranus are named either after william shakespeare or alexander pope characters i quite enjoy that like it's quite yeah oh and that makes sense when you know robert started talking about uh titania and oberon so yes that's immediately springs to mind okay yeah yeah so the main ones people might have heard of then like you just said that the five major moons that uranus has so yeah titania oberon and then you've got ariel umbral and miranda as well

and they all orbit like roughly aligned with uranus's equator so the orbit of those moons the orbital plane is tilted about 97 degrees to Uranus's actual orbit around the Sun. That's what Robert was talking about before when he said that when William Herschel discovered the moons, you could see them literally looping full circle around the planet rather than going in front of and disappearing like we see with Jupiter's moons, for example, because they're on the same orbit plane. Those five major moons would actually be classed as dwarf planets as well if they weren't like orbiting uranus right okay yeah although they are very small so titania titania however you want to say that's the eighth largest moon in the solar system it's only about half the size of

our moon so pretty small overall like the moon system as a whole then you've got 13 inner moons and they all share their origins with Uranus's really thin ring system. I think people forget that Uranus has got rings, which is quite exciting. And that's including like little Puck. People might have heard of Puck before. Yeah, one of Uranus's moons. It's classic.

Yeah, so Puck is one of the inner moons. And all of those moons, like their orbits are very chaotic. They're always changing. There seems to be lots of collisions that have happened in the past as well and there's collisions sort of predicted in the future given sort of what we've looked at in terms of their orbits like millions of years into the future but so don't get too excited how can an orbit change like what's happening yeah it's just the interaction between the moon and uranus or then the moons you know with each other as well so it's just all the gravitational pull especially when they come close to each other and then apart again

you get these tidal interactions which can start to pull on them as well and so you remember when we were talking about say jupiter's moons being in resonance and being pulled into resonance slowly over the years i think that's what the moons are trying to do because they're so close to each other but so you do have a very chaotic sort of system in there but then conversely to that you've then got on the outskirts of the system of Uranus you've got nine what's called irregular moons and they have really inclined orbits some of them are retrograde orbits as well which means they orbit around Uranus in the opposite direction to which Uranus spins okay they're very large distances away as well and so it's very likely that they're like captured asteroids so you know they're going to be pretty small things and like i said before as far as we know uranus's moon system is the least massive of

all the gas giants um so if you add up all the mass of uranus's moons you actually get less than 15 of the mass of our moon oh wow okay yeah so it's not the flashiest of systems but there's some really interesting physics going on there you know another reason to send a mission yeah it might not be the flashiest but it definitely sounds chaotic yeah just like what is going on um and we call uranus an icy giant so just how cold is it yeah i think i mean it really is the definition of icy giant so it's the lowest minimum temperature ever recorded in the solar system or any of the sources from planets was recorded on uranus it was 49 kelvin that's about minus 224 celsius or minus 371 fahrenheit for all of our

listeners across the pond and although like the average on neptune tends to be colder than the average on uranus so about 72 kel Kelvin up minus 200 degrees Celsius on Neptune. The sort of combination of the fact that the internal heat from Uranus is much lower than all the other gas giants, and that's because we think it has this rocky core at the centre rather than sort of gas all the way down like the gas giants. Although there's still a lot of debate about that. I feel like, Robert, you very confidently stated that in your intro.

We're like, no, we think it's rocky because of this. But yeah, who knows? Yeah, I mean, we can't look inside directly, can we, right? Exactly, yeah. But to give you some context, we think the interior of Uranus is like 5,000 Kelvin as opposed to Jupiter's core, which is supposed to be 24,000 Kelvin. And we know that because we can look at the amount of infrared light that the planets are sort of giving out. And some of that will be the infrared light that they reflect from the sun and some of it will be from their own internal heat. And Jupiter and Saturn,

they all give out more infrared light than we know they get from the sun. So we know they're hotter in the core. Whereas Uranus basically is just reflecting back the sun's infrared light and it's giving us nothing else extra. Okay. So we know that it's sort of very cold sort of in its interior. But also the low temperature due to that really large tilt as well because, you know, it's daytime for one pole for half of Uranus' orbit, which lasts like 40 years,

and then it's nighttime for another 40 years for the pole. So you don't get a lot of temperature change within the atmosphere itself because the sunlight is so constant on one area. So it means you then get obviously a lot of ice in the atmosphere too. Mostly it's in methane ice as well, which gives us that really turquoisey glow.

So very cold, lots of ice, definitely an icy giant. In 1777, I feel like that should have been like some sort of hamilton star 1777 william herschel moved to bath to make his name as a musician and was later joined by his sister caroline now outside of performing the herschels developed a passion for observational astronomy with william even making his own telescopes in their kitchen but it was in their garden in 1781 that William Herschel first discovered the planet Uranus. And luckily for us, the Royal Astronomical Society still has his notebooks from that time. So I headed off to meet our friend Sian Prosser, the Society's librarian, to see them for myself. I've brought out some documents from our archives. and the jewel in the crown of the archives is the Herschel family papers.

We have William and Caroline Herschel's original observations of various solar system bodies and nebulae and I've brought out some documents which are particularly relevant to today's podcast. Tell us who are the Herschels and why are they so important to the Royal Astronomical Society? William was actually our first president. It was his son, John, who was one of the founders of the Royal Astronomical Society. William Herschel was brought in to be the first president in 1820, 1821, but he died in 1822. He never actually presided over a meeting.

And Caroline Herschel, her work was so valuable to members of the Royal Astronomical Society. She was recognized for the massive contribution she'd made to astronomy by being awarded a gold medal in 1828. She was the first woman to be awarded the gold medal by this society. And in 1835, she, at the same time as another scientist, Mary Somerville, was made an honorary member. Women were not elected as fellows until 1916, but Mary Somerville and Caroline Herschel paved the way. This is how you've got your hands on all of these notebooks. Yeah, one of the reasons is because the Herschel family decided to donate some of these key

astronomical papers starting from the 19th century. Okay, so let's dive into them. So what we've got are these big A4 beige covers. The first one here is journal number one from March 1774 to September 1779. Are these all of the different notebooks that were used to observe what we now know as the planet Uranus? Yes and I just wanted to share with you that there's not one single observation, but I can show you the earliest observation, which is in a series of notebooks called the journals. Journal number one starts from March 1st, 1774. At this time, William Herschel, composer, music teacher in Bath, has become incredibly interested in astronomy to the extent that he is making his own telescopes and when astronomers start looking at the sky they're very often drawn to incredibly fascinating objects like saturn that is in fact the first thing that he observes in this first page of this first notebook saturn's ring appeared like i can't read that

saturn's ring appeared like two slender arms oh yeah and the pages themselves are like this lovely sort of tea stained color aren't they but you can see there are little sketches everywhere and and so he would be taking enthusiastic observations and writing down literally what he could see and dating it and making those measurements but then it was Caroline who would take almost those rough notes and put them into a perhaps more scientific write-up. At what point does this then turn into the first observations on Uranus? So I'm going to look at volume two. There's an underlined phrase here. It says on the inside front cover,

this volume contains the original observation as it was written at the time of the discovery of the Georgian planet. See Tuesday, March 13th, 1781. Shall we go to that page? Oh yes, let's go to that page. Oh my goodness. Okay, so Tuesday, March 13th, 1781. Shall we go to that page? Oh, yes, let's go to that page. Oh, my goodness. Okay, so Tuesday, March 13th. In the quartile near Zeta Tauri, the lowest of two is a curious either nebulous star or perhaps a comet. So he thought it could be a comet then or some sort of star.

So on the 17th of March, if I turn the page, it says, I looked for the comet or nebulous star and found that it is a comet for it has changed its place. We can have a look at his first write-up, which is published in the Royal Society's Philosophical Transactions, the world's first scientific journal. I have a volume of it open at the relevant page here if you want to take a look at that yeah absolutely so the title says account of a comet by mr herschel communicated by dr watson of bath and it was read on april 26 1781 so just a just six weeks or so after the initial discovery and it says on Tuesday 13th of March

between 10 and 11 in the evening while I was examining the small stars in the neighborhood of H. geminorum I perceived one that appeared visibly larger than the rest being struck with its uncommon magnitude I compared it to H. geminorum and the small star in the quartile between Auriga and Gemini and finding it so much larger than either of them suspected it to be a comet. And then he talks about how he used eyepieces of different magnification to examine it more closely and he says, from experience I knew that the diameters of the fixed stars are not proportionally magnified with higher powers as the planets are because basically this new fuzzy object looks like a disc it's not a twinkling point of light he knows it's definitely not a star but there's no suggestion

here that it's anything but a comet so far so So when does that change happen? When does he start to think, well, actually... To demonstrate that, I've brought out another volume from a series of notebooks in the archive, which demonstrates, again, the role that Caroline Herschel played in William's observation work and in defining his legacy. A few decades later, at the beginning of the 19th century, William asked Caroline to go through that series of rough journals and extract everything into one notebook per solar system body. And in that series, we have this.

Oh, wow. So we've got another of these handwritten notebooks, and on the front cover it says, Observations on the Georgian Planet and its Satellites. It's incredibly neat, isn't it? Caroline Herschel's work in particular is great to share with primary school children. They can read out for themselves firsthand what it was like to be an astronomer in the 18th, 19th century and grappling with bad weather, with things not being what they first appear,

with all the frustrations, and really importantly, with keeping a record of your observations and testing your hypotheses, which is just fundamental to science education today. Absolutely, and even here I can see, I took the diameter of the comet, and you can see some calculations here, and there's a diagram as well. And as we turn the pages, the following year, in 1782, he's constantly observing, and then he says on February 7th, 1782, it now appears this new star is a primary planet of our solar system.

And then he puts a little arrow and inserts, probably. A few months later, though, he becomes more confident. On August 29th, 1782, he says, I saw my planet full as well-defined with 460 magnification as Jupiter would have been at that altitude with the same power. Brilliant. Oh my goodness, I'm so excited. I can't believe I'm seeing this. It was a sensational piece of news.

This was the first time that a planet had been discovered since antiquity. And one way in which William Herschel caught the attention, not just of the astronomical community, but of royalty, was to name this new planet after King George III. That is why we keep seeing the words Georgian planet. That is how it was initially named. And how well did that go down well it went down extremely well with king george iii i'm not surprised by that yeah but what about the people outside of england because fair enough that was uh the herschel's king but it's not the king for

everyone else and the planets almost sort of go beyond that royalty and monarchy of one country so what was the wider community thoughts on that? It was suggested by other astronomers that a different name could be used. Johan Ellert Bode said you know Jupiter in classical mythology is the son of Saturn. Why don't we name this new planet after Uranus, the father of Saturn? And then we have this mythological family tree respected in the order of the solar system orbits. By the early to late, mid 19th century, it was generally known as Uranus. Okay. Regardless of name, the Herschels and William and Caroline were saying, right, there is this planet. Did they encourage other people to make those observations

and look at it as a planet and try and almost back up what they had done already? Absolutely. He had the attention of the astronomer Royal Neville Maskelyne now, who had great continental connections and encouraged his contacts in observatories around the world, primarily on the continent, to see if they could establish what was happening with its orbit. And it was because of William's observations and the observations of other astronomers that they noticed that instead of having a strongly elliptical orbital path, like a comet, the orbit was more circular.

And that was what led them to understand that this was a planet. This is the Supermassive podcast from the Royal Astronomical Society with me, astrophysicist Dr Becky Smethurst and with science journalist Izzy Clark. This month we're talking about Uranus but before that I'd like to mix up our space book club and turn it into a space content club because I basically haven't over the summer I haven't read any space books but I've gone to like fun little exhibitions and things like that so I'll throw this over to you two. Have you got any space books but i've gone to like fun little exhibitions and things like that so i'll throw this over to you too have you got any space related tv shows books exhibitions concerts

whatever that you would recommend yeah sure um so i feel like i have to go for the first one in terms of tv shows uh tim peak secrets of the universe on channel five is on september october at the minute and this might be a shameless bit of self-promotion because if you watch one of the episodes you might spot me chatting about black holes for five minutes but still i love tim peak he's absolutely fantastic obviously it's the astronaut tim peak who was up at the space station a few years ago now um has made this documentary about what we still don't know about our universe also the hunt for life things like that and it's a great great watch can highly recommend it if you fancy more of a like a proper documentary style thing then netflix have got a great documentary about uh jdbst the james webb space telescope at the minute that's called um unknown

cosmic time machine which um a lot of people have been saying is great watch i've watched a little bit of it and been really enjoying it and then also you didn't you didn't sort of prompt us with music izzy but i'm gonna add some music in there and this is a real oldie but a goodie but you know what i absolutely love it and people have to go listen to it um and that is public service broadcasting's space race album i was really hoping you would say that it's just fantastic i know what's coming i i literally if i need a boost i'll just put it on and i'll just like i'll just sing along with it well as much as you can sing along with it but uh that is public service broadcasting's album the race for space so if you don't know who public service broadcasting is they essentially take like old

public service broadcast audio usually from like you know hello hello, this is the BBC kind of thing. And they set it to music. And so they've got a load of that from the 60s, you know, going all the way from the Race for Space, Sputnik, Gagarin, going into space for the first time, you know, and then also like Apollo 11, landing on the moon,

which is one of my favorite tracks on the album as well. It's called Go. And it's just, again, just joy in a song. I was just about to say, so i went to the first ever blue dot festival so this is a music and science festival at the jodrell bank observatory another thing we highly recommend yes also go to that and public service broadcasting were playing that and having such like a lovely nerdy really enthusiastic crowd shouting along

to go was just such a highlight from that festival i will always remember that because it was it was just incredible yeah and then to have the level telescope in the background was just like you stop and have one of those moments like yeah i'm i'm very good here this is a nice time to give people if you people who've never heard the music just to give you an idea the go idea comes from the fact that if you listen to the audio back from sort of ground control for Apollo 11, they're like, Capcom, Go, guidance, Go. They're saying they're all ready,

like all of the different sort of areas of ground control. And it's just the Go becomes the most joyful thing you've ever heard in your entire life. Like, it's just incredible. I'm definitely going to listen to that after this episode. Robert, how about you? What would you recommend? Yeah, I was thinking about this.

I mean, in terms of books, well, like you, I've actually sort of read a couple of astronomy books over the summer, not very diligently, but one I'm looking forward to that I haven't read yet is by Dani Robertson, who's a national park officer and dark sky campaigner. And she's written this book called all through the night about protecting darkness and how it connects to human and animal life and insect life and so on so i'm gonna recommend that without having read it but it looks like it's got

good reviews so far from the people who have been able to do that in terms of cultural stuff i was thinking about films i thought are there any films coming out and then i i harked back to one from a while ago inter Interstellar, which if you haven't seen, I do recommend because the science content is quite fun. I mean, obviously it goes into the realm of artistic license, as you would expect, but it brings in black holes and time dilation and travel to other planets as well.

I guess also connected with that, if you want thinking of music as well hans simmers stuff associated with that is always you know very evocative too uh i really love that you know he also did stuff for things like um the podcast 13 minutes to the moon and that kind of thing too it's really really always just worth catching and then another thing i also haven't seen yet although i have been in the past is each year in greenwich there's the astronomy photographer of the year connected with the observatory in greenwich and that's what's fantastic it gets people from all over the world essentially amateurs although you look at it and you say really you know these people

are basically like professional astronomers when you look at the quality of the content but the the judges assess presumably thousands of images from around the world and select the very best images of the night sky the sun landscapes under the stars the northern lights all these kind of things and it's always a really special thing to see and of course the whole greenwich site is you know what i say this having worked there for eight years a while ago you can kind of describe it as one of the spiritual homes of western astronomy so i always recommend going on there for that alone i love that i love that exhibition um i'm hoping to go and see it next week but i need to i need to come back to the film uh suggestion there because

becky had such a reaction to that just like while you're talking becky shaking her head you redeemed yourself with the exhibition but i was like okay i agree with you on that one but i was like i cannot in good faith recommend Interstellar the film to our audience because I have right okay film craft

brilliant cinematography brilliant soundtrack brilliant like editing brilliant everything else

storyline no like a simulation of Black Hole made to look like you know we look if we could see it

like great everything else like you know we always look if we could see it, like, great. Everything else is... Like, you know, we always take the mick out of Marvel films so we're just putting quantum in front of everything just to, like, get away with no explanation. But I feel like Interstellar does that as well and it frustrates me so much. Why?

I'm much more forgiving, clearly. Well, I mean, on Interstellar um every summer the in the uk there's this the prom series on the bbc which is a series of music concerts and they start doing these late night prompts which start like quarter past 10 and i went to one which was by anna lapwood who's um an organist at the university of cambridge and she did this amazing concert called the moon and stars and so it was taking music where composers had been inspired by the night sky and things like that but they also she also played three installments of the incredible like organ music from interstellar so at the beginning of the concert it was one of like the the quieter

pieces and then halfway through you feel the tension building up and at the beginning of the concert, it was one of like the quieter pieces and then halfway through, you feel the tension building up and at the end, it was like the really epic thing. That's on iPlayer, right, as well? Yeah, it's on iPlayer. So it's Prom 15, Late Night, Moon and Stars. So it's, yeah, it's a good one.

And then in terms of exhibitions, I feel like we have to talk about the Herschel Museum in Bath. You can go to their house and stand in the garden where William Herschel first discovered Uranus like it was so not it's so good and I think for me so my parents are both musicians um but I've obviously ended up being a little science pal uh so I it's quite nice to see that combination of their life as musicians but also life as astronomers as well shall we get on to some questions so Robert can we start with this one from Justin Justin

wants to know what's the difference between Uranus's atmosphere and other planets in our solar system yeah just a good question it well they're all very different in a sense um but there are similarities and differences so uranus is an ice giant and so it is a gas giant like jupiter saturn and neptune and that means it was big enough to hold on to lots more hydrogen helium than for example the earth does so it has a lot of that not terribly different to the um the atmosphere of the sun in some sense in the proportions because it hasn't it's not a star so it's not been processing that hydrogen to increase the content of helium over time not fusing it which is what what powers our sun you also find methane and other traces about different elements as well and then lower down like the other gas giants but with a different kind of

temperature profile that kind of thing becky was talking about earlier on the compression under gravity probably turns that into a liquid there's probably a sort of liquid water ammonia ocean deep down completely exotic and then possibly below that this solid core so the distinction I guess as well is that as again as Becky and Lee and Sol mentioned it doesn't appear to have the same kind of internal heat source as the other giant planets. So the atmosphere also doesn't have the same sort of weather systems all the time. So when the only space probe went there in 1986, Voyager 2, which I remember quite well because actually they had an exhibition in the Herschel Museum in Bath, the atmosphere looked very bland. It looked really smooth, beautiful

blue, but there were virtually no cloud features in there. However, as the seasons progressed and you started to see this temperature change, because remember it's tilted on its side, as that went round and the equator was exposed to the sun and you started to see more of a shift in temperature, you saw much more in the way of weather patterns and spots and features and so on. So I guess the main distinction, I think, if I think about its appearance at least, is that Neptune, Jupiter and Saturn all consistently have much more active weather features and uranus sometimes just doesn't and sometimes does thanks for that robert i'm becky space dambapdx asks do we know why uranus's storm spot disappeared so i'm not sure which spot that they're referring to because

there's been a few like dark spots bright spots clouds polar vortexes like spotted in uranus's atmosphere over the years you know but none have been say as long lasting as like the great red spot on jupiter for example and we think that's because you know the atmosphere of uranus is just so cold as we mentioned before so there's not as much mixing, you know, there's no like convection where you have the heat rising and the cold falling that produces sort of, you know, clouds and give us weather patterns here on Earth. So it really does limit the amount of then weather features that you see on Uranus in the form of, you know, these dark or cold spots. Plus, there's not as much of like a temperature change due to the fact that you do have that

constant sort of sunlight flux on the pole for, know decades at a time as it points towards the sun and so that just all results in this fairly sort of uniform looking planet with short-lived features which i presume is why we constantly overlook uranus because it's not that exciting in looks anyway it's got lots of core physics going for it. Okay, okay. And Robert Rennan the Geek asks, is it true that it rains diamonds on Uranus? Why? Well, the answer is we think so, Rennan,

although with no easy means of finding out for sure. And the idea is that in this mantle region, which is that ocean must be better described as this ocean above the planet's core that we talked about earlier on we think that the methane gets broken down and relatively high temperatures there and pressures you get the carbon freed from that that gets sort of super compressed and then the higher temperatures cause it to evaporate within this mantle ocean and all within this ocean feature that rises up, cools down as diamonds and then rains down again. And we also think that probably happens on Neptune as well.

And there are some suggestions even at the base of the mantle above this possible solid core in the centre, there might even be diamond bergs floating around as well. But yeah, whether or not it seems essentially inconceivable we could ever actually see these things get that mission to uranus please and i'll just take a little net and just be like okay i'm just gonna collect all the diamonds thank you very much um becky mariana and quite a few others actually want to know why does uranus have rings and what are they made of yeah so uranus does have rings. They're not as complex as like Saturn's rings, for example, but they're much more complex than the very simple rings of Jupiter.

Now they're thought to be fairly young, you know, around about 600 million years old. So it's ring chickens in terms of the solar system, you know, they were around at the time of the dinosaurs. And we think they were formed by a collision between those inner moons, you know, the ones we were talking about before they're very chaotic orbits everything like that so unlike saturn's rings which is sort of very tiny ice and dust particles we think that uranus's rings are made of like big chunks of old moon you know from like

20 centimeters to 20 meters across so that's most likely big chunks of ice but perhaps big chunks of old moon, you know, from like 20 centimetres to 20 metres across. So that's most likely big chunks of ice, but perhaps big chunks of rock too. But they are incredibly faint, Uranus's rings. They reflect as much light as charcoal does, just to put it into context how faint they are. Flying! Yeah, so they were actually only discovered in 1977, which is crazy to think. Although William Herschel apparently did claim that he could see rings around Uranus, but modern day astronomers doubt that claim considering how faint they are and the fact that you tend to not be able

to see them with a similar size of telescope as William Herschel used. Of course, maybe the light pollution was less during those times and we can't redo the experiment with the exact with the exact same conditions but you know people do doubt that he was able to see rings around uranus well there we have it and if anyone's listening to this and thinking oh i have a question then do email us you can do so on podcast at ras.ac.uk tweet us at royal astrosoc or find us on instagram it's at supermassivepodPod. Yeah, and if we don't answer them in a main episode, don't forget we do have our little bonus episodes where we maybe answer the questions that didn't fit into an episode's topic. So make sure you listen to those as well.

And October is a big old Q&A. So send them in. Send them on. So before we get on to stargazing with you, Robert, I need to ask you both did anyone see comet nishimura no i haven't not yet so sad robert i tried i tried i got up at different times um i tried in the morning and in the evening and no i haven't i mean theoretically it's still good but i suspect it's not gonna be it was wasn't it just wasn't really low it was too low there were

there were clouds in the way always low on the horizon but there are really good photos some people do i don't know if anybody's seen it i think maybe one or two people have seen it with their eye but people have seen binoculars but there are nice photos of this this little green comet i mean not little really you know the difference between nearby and far away right but yeah there are photos but no i didn't you know what we did see this month though izzy which i think you guys will enjoy i was at a conference down in the boot of italy place called trapeia with like you know 70 other astronomers at a welcome drinks reception when starlink went over oh like recently launched you know a big chain of them across the sky almost

looked like you know like lots of uh international space stations going over in a chain they were so bright and like the the sort of atmosphere on this sort of balcony where they were having this drink reception was like oh wow look at that and then we were like oh it's starling and you could just tell like the atmosphere in the room of 70 astronomers was like yeah mixed feelings on that one yeah exactly it was like that's so cool and yet no yeah i remember seeing it in marrakesh i think i've told this story before but um we they have a lot of restaurants on the roofs and so my partner and i were on the roof and just saw it go overhead and i was like what's that i was looking at it's like oh that's starlink but people on the table next to us suddenly clocked that we were looking up at the sky and got really stressed about what it was because they didn't know what it was. They're

like, oh my God, what is that? I was like, no, no, no. I was like, don't worry. Well, actually, maybe worry a little bit, but okay, so let's move on. So what else can we see in the night sky this month, Robert? Yeah, I mean, there's a fair amount going on, really. We're're getting past the equinox so the nights are drawing in and that means it's getting dark earlier and at the end of the month the clocks go back so it gets dark even earlier and the constellations of autumn are obviously nice and prominent now as well you've got andromeda stretching away from the square of pegasus really obvious in the southern sky and if you're in the northern hemisphere it's actually not that hard if sometimes people ask how far can you see well you can see the andromeda galaxy from a dark site with your eye quite easily so you can see two and a half million light years if you know where to look and it helps if you have an app left

and up a bit from the square of pegasus and above that you've got perseus who in the greek myth slew the medusa who you might recall was able to turn people to stone just by looking at them. And then rescued Andromeda before she was sacrificed to Cetus, another autumn constellation, the not-so-friendly whale. And then above Perseus is the W of Cassiopeia. And in that region between Perseus and Cassiopeia, another thing to look out for is the beautiful double cluster of stars. They're a few thousand light years away, but if you have a pair of binoculars, you see this wonderful collection of two concentrations of stars, even with a pair of binoculars. And the planets are pretty good this month, too. Saturn is just past its best, but still really obvious in the southern sky in Aquarius. And Jupiter is starting to get better.

And a bit later in the evening, you can pick that out. Again, very obvious over in the east after the sun sets in Aries. very obvious over in the east after the sun sets in Aries and really got to say connecting to this episode not far away from Jupiter in the sky at all is Uranus now you're going to need a map or an app to find it it's not that bright you know and if you pick it out with your naked eye then you're doing really well you can easily find it with binoculars it'll just look like a star and if you've got a decent enough size telescope it looks like this tiny blue disc and it's quite beautiful you don't see any features but it's quite beautiful to see and if you want to get up early to see the the final planet that's okay really good at the moment is venus um i say early but obviously sunrise is getting later so if you're up and about just

before sunrise it doesn't even have to be properly dark then venus is really quite high in the eastern sky and very obvious and just you mentioned apps there I mean I don't I use Stellarium are you two the same I mean just if anyone does want to use that I use Stellarium and other people have different recommendations Stellarium's free and fairly easy to use it does things like if you hold your phone up to the sky and you twist it around then it it lines the compass and so on so it will show you exactly what you're looking at but there are others like that i mean there are paid apps too and all the rest of it but it has really i think made it much more accessible made it much easier for people to find things in the sky definitely the only thing i would recommend that if you have an app the only

thing it has to have is like a red light feature so you can completely like because obviously the glare of your phone screen is just going to ruin any night vision so if you have the sort of everything is in red it's not as sensitive to your eyes getting rid of all the blue light solarium definitely does have that as well even on the free version which is really good um and the final thing i'll mention is there are actually two eclipses this month as well so if you're in the americas in a swathe of north america right down through central america into some of Southern America. Then on the 14th of October, there's what's called an annular solar eclipse. And this is where the moon moves directly in front of the sun, but it's too far away to cover it completely. So in this

case, 91% of the sun will be covered. Now, I should stress that the ring of sunlight left behind will still be really bright. So you're still going to need the proper filters, certified safe solar filters to look at it. Otherwise, it's really dangerous to stare at it, particularly when you've got a thin ring of sunlight, because it fools your eyes into opening up your retina and it can leave you with permanent damage. But notwithstanding that, it's something to look out for if you live in that part of the world. And for us in Europe, and also in Asia, we actually get a partial lunar eclipse two weeks later at about 8.30 in the evening in the UK, at least on the 28th of October. And 6% of the moon will go into the darker shadow. So it'll look like a sort of red bite is taken out of the top of the moon.

And the rest of it will have this yellowish color because the outer shadow, what happens in a lunar eclipse, I should say, is the moon is moving into the shadow of the Earth. And the outer shadow has a kind of yellow quality, theumbra so do look out for that too and if you get some photos they are usually quite photogenic then then tweet us or say i call it the sunset shadow oh nice you've got the main shadow and then the sunset shadow nice and it's a beautiful red color it's absolutely fantastic yeah exactly yeah well come on 28th of October. No clouds are allowed. Thank you very much. I sadly won't be in the UK, so I'm going to miss it. Where are you off to? I'm going to be in the Maldives.

Oh, well, I don't feel that sorry for you. It might even be visible in the Maldives. Well, I was just about to say, yeah. Yeah, I'm really hoping to catch a glimpse of all four gas giants with the telescope that I know I'm going to have there, so that'll be really fun. I'll report back. Oh, yeah, send us pictures, please. Thank you very much.

I think that's it for this month. So we'll be back with a bonus episode in a few weeks time. And then, as I've said, we'll be bringing a special Q&A episode. So just send us all of your questions, basically. All of them. Like anything that's ever kept you up at night. Astronomy related. Astronomy related.

Please send us. Yeah. So, you know, you can tweet us or you can send us an Instagram DM if you try some up at night. Astronomy related. Astronomy related. Yeah. So, you know, you can tweet us or you can send us an Instagram DM if you try some astronomy at home. It's at Royal Astrosoc on Twitter. Or you can email your questions to podcast.ras.ac.uk. And as Izzy said, we'll try and cover them in a future episode. Until then, everybody, though, happy stargazing.