The Supermassive Podcast - 3: Our Neighbourhood Star

Episode Date: March 19, 2020

This month, Izzie Clarke and Dr Becky Smethurst explore the star in our neighbourhood, the annoying habits you would banish there and the extreme stars further afield. Plus the Royal Astronomical Society trusts them with a very special book from their archives: Caroline Herschel's star atlas. What annoying habits would you banish to the sun? Or have you tried some Astrophotography at home? Share with the team via [e-mail] or tweet @RoyalAstroSoc. With special thanks to Professor Lucie Green from University College London and Royal Astronomical Society librarian, Sian Prosser. The Supermassive Podcast is a Boffin Media production for the Royal Astronomical Society. 

That doesn't sound super massive, that sounds very small. I can't carry on now. Yeah, okay, it's a pretty normal star, but I wouldn't necessarily call it average. Space is so cool, but it is a little bit terrifying. I would just like to point out that this looks nothing like a whale. Sunspots, what are they? Rule number one is do not look at the sun. Hello, welcome to the Supermassive podcast from the Royal Astronomical Society

with me, astrophysicist Dr. Becky Smethurst and science journalist Izzy Clark. How's it going, Izzy?? Yeah I'm all right thanks. I had a bit of an odd journey in where someone was I would I wouldn't say it was singing along to their music they were listening to really heavy rock music like Slipknot and were just like shouting on the tube which was an unusual morning and an unusual start to the day. A scream along would that that be? Yeah, I don't know. I wouldn't say it went down very well. But no, overall, pretty good. And I'm really excited about today because we have got so much in store.

I mean, this month we're exploring the star in our neighbourhood and those further afield. And the Royal Astronomical Society are trusting us with a very special book from their archives. Is that wise considering your track record? Well, it's no damage so far. But when it comes to studying our sun, rule number one is do not look at the sun. Oh, now you tell me. I guess it's like when you see someone famous, you're like, don't look at them. They're not there. What, like never meet your idols is the same as don't look at the sun?

Maybe that just shows if I saw someone famous, my instinct would just to be run. Look away, run away. I'll make a fool of myself. Just imagining one day like you walking down the street and just like happening across like the Spice Girls and just running in the other direction. I can't, I can't possibly. But with us here is Robert Massey, the Deputy Director of the Royal Astronomical Society. Okay, so no looking at the sun directly, we've learnt that.

But if there is a solar eclipse, you get those jazzy glasses, essentially. They look a bit like sunglasses. And that means you can see an eclipse. So how do they work? How do they work? Well, you have to, I mean, and I have to stress, they're not sunglasses. You know, do not use sunglasses to stare at the sun. If you get an eclipse, it's a long, long time before we have a total eclipse in the UK.

And during totality is the only time when it's safe to look at the sun without those glasses. But they filter out all but about one part in 300,000 of the light coming through. And they filter out all the ultraviolet as well. And that's why it's safe to look through them but even then the caveat is that you shouldn't use them if they've got scratches or holes or anything like that or if they're in any other way damaged and I remember the advice on this in the eclipse in 1999 in the UK which was relentless and you know and hardly any there were a tiny number of people had some problem but basically as a result of looking at it without glasses and being unsafe there are better things you can do well. I always think that if you're just looking at a partial eclipse,

which is where the sun isn't completely covered, or if you just want to look at sunspots generally, it's a good idea to project the sun through a telescope or a pair of binoculars. You can do that really quite easily. Mount them on a tripod so they're stable. Put a bit of white card behind. Do not, do not, do not, do not, do not look through them because that will obviously damage your eyes.

You're focusing all that light into your eyes it's a really crazy thing to do but if you do that you set it up and if you've got children around you obviously make sure they don't look through it either then you get a really great view and it's not that hard actually you point them at the sun you minimize the shadow on the on the screen you've got and then you you should see the image of the sun you focus it it'll be quite big and it's a really relaxing way to look at it so i strongly recommend that if you're watching just a partial eclipse which in the uk you will be until 2081 uh beyond the life of this podcast i'm guessing or most of the present one maybe not you guys but certainly i'll still be getting you guys will still get out my telescope i'll be cracking out my colander because that's

one of my favorite things to view an eclipse with is a colander like what you drain vegetables with you know the method you can hold it up like sort of over your shoulder with the sun behind you and it projects down and you can see like instead of circles where all the holes are, they're little shapes of what the projection of the eclipse is. And it's just my favourite thing in the world.

Oh, that's brilliant. Do you remember seeing your first eclipse? I saw my first total eclipse in 99. I was in the Middle East in Iran and I saw, I've seen about three since not not some for quite a long time now actually but uh and the first partial one i saw i guess it would have been the 80s or the 90s something like that using that method i described actually projecting with a small telescope um you can also get filters that go over the end of telescopes

they're quite they have to be from reputable manufacturers obviously this isn't something you're going to knock up yourself uh and you can buy those online and get them to fit the telescope that will give you a good view as well but again i stress you know they've got to be in good shape get them from somewhere reputable and put them over the end because if you put them the eyepiece you're focusing all the heat onto it they're much more likely to be damaged and if you have a tiny crack it's a real problem but you do get a fabulous view when right now the sun is not that active we haven't got many sunspots you can see but when it is it's it's a really great. We haven't got many sunspots you can see. But when it is, it's a really great way to see them.

And some of the drawings you can see here at the RAS, for example, were done by people using exactly that method. It shows how dynamic and changing the sun is, isn't it? I think it feels like it's just sort of this big yellow ball that's very constant. And as soon as you see it through any sort of projection or a telescope with a proper filter, it's amazing what you can see. I remember running to the park with all my family for the 99 eclipse and just everyone was so excited i it just stands out in my memory as one of my earliest astro experiences i guess i think

it was one of the first that like made me become an astronomer actually my mum always says that those glasses you know we got them free from school and i just didn't take them off for like three days afterwards i just wanted to wear them the entire time blundering into furniture exactly it was so dark it was crazy but I thought it looked amazing at nine years old but um I remember that I clipped so vividly like standing outside in my garden it wasn't totality where I was like up north but it it was it did get quite dark and I can't even imagine how dark it must get in complete totality. It's a very eerie thing.

So just before totality, you get this sort of weird deathly purple colour across the landscape. It's very strange. It may well be an optical illusion, I don't know. But in totality itself, it's about half as bright as the full moon, roughly. So it does get pretty dark. You start to see a few stars around. But the sky around the horizon is quite bright because the shadow is not not huge you know it's not covering the whole earth so

it's it's a absolutely recommend you get to see one it's a very strange thing to look at cheers robert we'll catch up with you later in the show for less sun gazing and more star gazing now let's face it we owe a lot to our sun without it the earth would be an ice-coated rock and we certainly would not be here. But just how much do you know about our neighbouring fireball? It's over to Professor Lucy Green from University College London. Answering the question, what's the sun made of, actually was a really hard question to answer. And we didn't know until 1925 that the sun is made mostly of hydrogen. So we knew it was hot is made mostly of hydrogen so we knew it was hot or the scientists at the time knew it was hot knew it was giving off light but that question of what's

its composition and it was hard to answer initially people thought that the sun was made of the same material as we see around us like iron but it was Cecilia Payne Kaposchkin who in 1925 looked at the light coming from the sun and was able to determine that it's mostly made of hydrogen and then some helium and then a very small quantity of other elements. And so just how hot are we talking here? Incredibly hot. When it comes to the centre of the sun, we're talking 15 million degrees. And those numbers, it doesn't even matter what units you use, but let's use

Kelvin because that's the scientific scale. So 15 million Kelvin in its core. And then gradually, as the energy is trickling through the sun, when we get to the surface, it has a temperature of 6,000 Kelvin. Then weirdly, in the atmosphere of our sun, the temperature starts to hike up and it goes up into sort of the low millions but you know it's all incredibly high oh so it goes really hot you know still very hot but then even hotter on an outer layer yes that's right and this was one of the amazing discoveries of the space age is that the sun's atmosphere is hotter than its surface and what we've come to understand now is that the the reason for that is that the sun not only being made of a plasma, also has this complex magnetic field threading through it. And that magnetic field can channel energy, store energy, release energy.

And ultimately, we think it can heat the atmospheric gases to these millions of degrees. And do we know how old the sun is? Where did it come from? We do. So there's lots of pieces of evidence that we can use to work out how old the sun is but when you bring them together it seems to be four and a half thousand million years old so four and a half billion years and we think it's about halfway through its lifetime and you can do things like um dates other objects in the solar system that we can

touch and and analyze because we know that the solar system, the sun, the planets, asteroids, all formed ultimately out of the same cloud of material. So if you date asteroids that come to the Earth, then you can figure out how old they are. And by the process of knowing that everything formed collectively, say, OK, the age of the asteroids is also the age of the sun and it's about four and a half thousand million years now compared to other stars where does it sit because we get a lot of different sizes don't we so size wise we certainly see stars that are more massive than our sun but equally there are stars that are you know 12 times less massive than our sun. So our sun sits on a spectrum

in terms of mass, in terms of size, and in terms of temperature. But even though when we look into the universe, we see stars that have much more activity than our sun. So our sun is an active star. It has these eruptions and explosions in its atmosphere. And other stars have much more energetic eruptions and explosions. Other stars have And other stars have much more energetic eruptions and explosions. Other stars have magnetic fields like our sun does. But I think what makes our sun special is because we're up close and personal with it and we can study it in a way that you can't do with any other star. And it has an impact on our lives because of its proximity.

All these different stars, you know, they do go through a life cycle so where does that start and how does that end based on all of these different sizes of stars i think viewing the sun as being at a point in its life is a really lovely thing to do because it gives us this sense that they are transient even though to us on the earth they far outlive us they still have a life cycle so they're born stars are born out of huge clouds of gas and dust that for some reason start to collapse so maybe there's a distant supernova that sends a shock wave that just starts a little compression on the gas cloud and then gravity can take over. And because stars are being powered by, they sort of consume themselves,

they're using the hydrogen that they're made of in a process of nuclear fusion to change that hydrogen into helium. And so when the hydrogen runs out, that star starts, it's the end of its life. And so this is a question uh that gets asked quite a lot because we've seen apocalyptic films and is there any chance that our sun will one day just you know explode and then that that's the end of it that's the end of us and everything that comes with it if we have not got an escape plan by the time our sun dies, that will be it for us, for sure. And when our sun dies, when it runs out of fuel,

it will go through different phases. But one of the phases it will go through is to become a red giant. And that will coincide with a time where our sun expands, becomes much, much bigger. I'm not sure of the latest estimate, but it will probably expand to the size of the Earth's orbit around the sun. So even as that process is sort of, you know, beginning, the sun will become bigger. On Earth, we will be feeling hotter, we'll be getting more radiation. So our oceans will start to evaporate, there'll be more water vapor in the atmosphere,

which acts as a greenhouse gas, which holds more heat in. So there's this sort of process of the Earth becoming a scorched, dry planet that we will not be able to exist on. So yes, I am afraid that in several billion years from now, the Earth is going to be a really unhospitable place. Yeah, it's quite a while off though. It is, it is. It's not something i lose sleep about for sure but to just sort of bring that journey of the sun to an end once the sun has gone through its red giant phase and it's and it's expanded it will throw off its outer layers and what's left behind is the remnant core of our sun that will be called a white dwarf the sun won't be generating energy anymore at that point it will just simply

be cooling and fading for the rest of the lifetime of the universe oh definitely glad i won't be around when that happens that was professor lucy green from university college london and she was potentially joining us today but there was a change of plan because she had to go to the u.s to interview commander chris hadfield which i guess is a pretty good excuse yeah not that i'm jealous or anything that she's there and we're here so yeah i mean you ask the best questions to our guests is he like sun exploding we had black holes and spaghettification in episode one like why do you always ask like the the like deathliest questions i mean no doubt space is so cool but it is a little bit terrifying you know it's just it's the questions everyone wants to know true yeah i like how that's your

mission in life is to capture the terrifying things about space just too much sci-fi in my life probably but brian cox has wonders of the universe and it's like new from izzy clark the terrifying things of the universe how How will space kill me? There are these really interesting features on our sun. We've mentioned them very briefly earlier, these things called sunspots. So what are they? Yeah, they're essentially like cold regions on the surface of the sun. And I say cold in the loosest sense of the word there.

They're not cold. They're cold in relation to the rest of the surface of the sun. But you can think of sort of the interior of the sun as this sort of big mixing ball sphere thing. That's a technical term. And essentially what you've got is something we call convection. So if you remember convection from school, it's basically like heat rises, right? So it rises, it cools, and then it falls back down again. So you get these sort of big currents of movement of gas and what is essentially plasma inside of the sun right which is gas that instead of you know being atoms you've taken the electron out of the atom and then the electrons roaming free from the center of the

atom right and so that's what we call plasma so because all that's moving you then set up sort of like electric charges and then because you've got moving like charges you've got magnetic fields and the magnetic fields of the sun is incredibly complicated and we don't really understand it and where it all sort of intersects and and tangles up you stop this nice convection process of the rising and the falling and so you end up with these cold spots where there isn't heat coming up from in the center and so they're they're these really cool structures they have sort of real, I don't know what the word would be,

like a morphology, like a shape to them that you're really not expecting. And they're so detailed as well. And that's just from the sort of telescopes you've got now. Like in the future, as we get closer to the sun with these new probes that are coming, we're going to be able to see such incredible detail

on these sunspots. And I'm so excited for it. Yeah, that's going to be great. I mean, and they really are, if you see a picture of the sun they are these sort of black spots of nothing essentially but obviously they are something but um and we heard earlier from Robert that the sun is very quiet at the minute which means it doesn't have many sunspots because these sort of appear in this 11 year cycle of where we see lots and lots of sunspots and then 11 years later there's not many sunspots so it's really interesting because we don't really understand where that comes from but we also know that it can have

some effect on sort of earth weather and the aurora and the northern lights and this is why we're still sending missions to the sun because we still don't know and that's a good thing because otherwise we'd all be out of a job now another thing that i found fascinating, and you know, we are clearly orbiting the sun. The seasons sort of give that away. Yeah, exactly. But one thing I hadn't really considered is that our sun is then orbiting a much bigger space. Exactly. Yeah. So the sun is orbiting the very center of the Milky Way galaxy. It's one star of billions of stars and it's moving at something like 200 kilometers a second as opposed to like the earth going around the sun at 30 kilometers a second so it's really kind of

a large speed that it goes round at but what i think people don't necessarily think about either is when they think of the sun orbiting the milky way and the earth orbiting the sun is that that doesn't happen sort of all lined up so the solar system is tilted with respect to where the sun goes around the center of the galaxy which means that the southern hemisphere always points towards the center of the milky way and the northern hemisphere always points out of the milky way which is why the southern hemisphere has such a better view than we do because the milky way because they're essentially looking into the center of the milky way yeah pretty much yeah but then that also means that because you know how we have the seasons because the earth's axis is tilted with

respect to the sun and everything we sort of have galactic seasons as well so if we wait long enough eventually in the northern hemisphere we'll point towards the milky way center oh my goodness can't wait for that to happen but it's in like hundreds of thousands of years. I'll be there. So for a long time, humans thought the Earth was at the center of everything. Then Copernicus came along and put the sun in the center of his new model of the solar system. But it was a while before we understood that the sun was not at the center of the universe and is in fact just one star in a galaxy of billions. One of the very first women to receive a salary as a scientist was German astronomer Caroline Herschel, who was one of the

first people to map the positions of stars in the Milky Way. Living in Slough in 1787, she received a royal pension of 50 pounds a year helping her brother William Herschel, who was royal astronomer at the time. To tell us more about her work is Royal Astronomical Society's librarian Sian Prosser. So Sian this is an incredible looking book we've got before us so what are we seeing here explain it to us. We are looking at a star atlas it was published in 1781 it's one of the later editions of a star atlas by john flamsteed who was the astronomer royal and it's a special book because it belonged to caroline and william herschel and they used it extensively in their observations this thing is absolutely massive yeah it's huge it's very

reminiscent of like sort of like uh artist portfolios at gcse or the kids that were doing art would go around these huge things right this is what this is to me and it's amazing because they've just i mean they've annotated it all over there's not a single page that you don't see these scribbles in the margins and scribbles where there's been numbers put everywhere as well is this are these all caroline and williams annotations that we're seeing here yes they are so the way that they used this book which contains really detailed charts of the positions of stars about 3 000 stars that john flamsteed identified that they used it to as a reference for their own observations and it's heavily annotated so we've got the page open ac mae'n cael ei anodd yn fawr. Felly mae gennym y llif ar-lein yn dangos y gynstelediad o Andromeda a Perseus,

gyda rhain gyda chyfnodau hynod o ddynol, yn dangos y ddyluniau mytholegol yma. Mae llawer o'r stair yn cael eu cyfrif yn Rhed Inc. Ac roedd hynny red ink and that was Caroline Herschel's numbering. She took John Flamsteed's catalogue of stars and a catalogue of stars is basically a list showing all of the coordinates of where a star might be found in the sky. It's much less visually appealing than a beautiful star atlas like this but absolutely fundamentally important to astronomy and she basically annotated every single star in the book based on this numbering system. beautiful star atlas like this, but absolutely fundamentally important to astronomy. And she basically annotated every single star in the book based on this numbering system.

As we said, it's this giant book, but there are these intricate drawings of Andromeda and Perseus with all these little dots around them and a grid just split up into chunks of squares to help coordinate and show the coordinates of where all these different stars are. I'm actually quite overwhelmed, I think, by seeing this. Yeah, even I, who's someone who thinks they know this part of the sky quite well, I'm quite overwhelmed just because of how much detail there is there. And one of the things that I just got really overly excited about, which is probably a little bit stupid, is that Caroline Herschel writes her fours the same way that I do. And I was like, oh, look at that. Yeah same okay we can join that club. The Caroline Herschel four club. So we obviously recognise Caroline's work today and we're

very excited to be in front of this incredible looking book but was her work recognised at the time mapping the positions of stars and identifying all the double stars in the list that were named as singles was that something that was recognised? It was. She was recognised for her work on the catalogue and on deep sky objects and on her discoveries of comets by the Royal Astronomical Society. So in 1828 she was the first woman to be awarded the gold medal of the Royal Astronomical Society and later on in 1835 she at the same time as Mary Somerville, was made an honorary member. The first two women to be made honorary members of the Royal Astronomical Society. Unfortunately, it wasn't until 1916 that women could be elected as fellows in their own right.

Can we see another page? Are we allowed to turn the pages? Can I see, like, Orion? That's my favourite constellation. Of course. I'm going to turn the pages really carefully because this is a really battered and well-used item okay so we're now on the page that shows orion and it yes it's very helpful scientifically but it's just a stunning piece of artwork really it really is like you can't help but just be in awe of you know this shape of orion the hunter that you're just like i've never thought that it looked like that before,

but it's just so beautiful. Like the detail and the sketching and the pencil lines, I guess, or is it an engraving you said? Like, it's just incredible that someone could do that much detail for, you know, picking something out of the stars. It's incredible. We've got that famous belt that we talked about

in episode one, and you can see those very clearly marked with circles. And then just below that belt is his sword and those amazing annotations. Oh, my goodness. And is this Cetus looping around here as well? I mean, I know Cetus is a big constellation, but seeing this sketched out before me as this depiction of Greek mythology, this huge big like sea

serpent it's huge yes you can see the edge of cetus i would love to show you the whole of that constellation because there's a nice anecdote related to that here we are it's the next page oh oh my gosh terrifying well it's funny you should say that because john herschel the nephew of caroline herschel also found it terrifying and in one of the family memoirs, it said that he would run up to her and say, show me the whale, auntie, because he liked to be horrified by this, you know, engraving of a terrible sea monster. I would just like to point out that this looks nothing like a whale. It's like if you took the head of an angry camel put it on the body of a bull turned its front hooves into webbed feet and its back end into a creepy mermaid

tail that that's what it looks like it doesn't look like a whale in any sense or description not only webbed feet webbed feet with claws so creepy amazing sean this has been such an honour to look at this book. Thank you so much. Thank you for your interest. This is the Supermassive Podcast from the Royal Astronomical Society with me, astrophysicist Dr Becky Smethurst, and with science journalist Izzy Clark. This month, the star in our neighbourhood, our sun.

Yeah, and if you want to send in any questions to us for a future episode, then email podcast at ras.ac.uk or tweet at Royal Astrosoc. Just like Zioz Dochka, who has sent us a tweet, and I love this question, it says, if we really wanted to fire someone into the sun. When is the next Opportunity launch vehicle? Robert is absolutely crying. I'm just thinking about potential candidates. No, but seriously, when is the next? Do we know when the next one is?

They've just missed the solar orbital launch. Unfortunately, we need to really look on, check the NASA website for schedules. But I think in the next couple of years, there are some solar missions. There must be, yeah. I'm'm sure it'll be fine we'll take a look into that but if there was one thing that you could send to the sun like you know some horrible habits we're now sending them to the sun what would you banish um i as someone who is now a person that walks around london i would banish people who walk down the street just sort of what I call theme park waddling do you know what I mean they're just such a slow waddle

from side to side and you can't get around them because they waddle one way and then they waddle the other way you're like yes I know exactly what you mean I think I need to get rid of the people who you know I know it's an accident but if they step on the back of your shoe as you're walking you're like oh god I've lost a train that way you know what I'm just thinking you're the waddler and that's me standing on the back of your shoe um excuse me I'm from London I am a fast walker how dare you what about you Robert I think I'd send those people who listen to things on coaches buses trains without headphones I mean really what is this about you know am I just old and grumpy? Probably yes. But really, seriously, do you need to do this? Unless it's our podcast, in which case they're very well.

Oh, yes, please send that up as loud as possible. And that is the only reason that you're allowed to do that. Now, Becky, can you clarify something for me, please? When I sent you over the running order, I said I had a surprise for you, and it's been brought to my attention of something that went down in episode two. So this was our episode all about relativity. And there are some things that you clearly feel very passionate about.

So the first thing we were talking about was Einstein's equation, E equals MC squared. Yeah, I mean, it's the most famous equation ever, right? I would I would argue is my hill to die on, right? It's the most famous equation ever, right? I would argue. That's my hill to die on, right? It's the most famous equation ever. But then we got talking about the Royal Astronomical Society's new logo. I love the new logo. Like, this is the hill I will die on. I have two hills that I will die on.

Okay. Ultimate battle. Which hill will you be choosing? I'm sorry, Royal National Local Society, but I think E equals MC squared beats the new logo. I'm sorry. You can't argue with that one. Really, what can I say, frankly?

Somebody doesn't value our logo as much as the semi-legal. Hey, work E equals MC squared into the logo, and then I'll let it fall. Becky's not prepared to defend a whole mountain range of ideas. Apparently I'm just a very overdramatic person with many hills to die on. You're just so passionate about space, it's fine. Okay. So we've been talking about our sun and stars further afield.

So our sun is pretty average. So the sun, I guess, is average in the fact that it is part of its normal lifetime of a star. It's happily burning hydrogen into helium and it's sort of not bothered at all. And it's pretty stable and it's pretty happy doing that. In terms of sort of like how big is it? Like, yeah, okay, it's on the low end of sort of the mass of stars.

But I mean, all sort of stars that are in that sort of normal lifetime are just gonna be happily burning their fuel no matter how big they are necessarily. It's just that the big ones will run out a bit quicker um but at the end of the day like it yeah okay it's a pretty normal star but I wouldn't necessarily call it average I would call it normal because it's there are a lot of weird stars out there we'll get onto those ones and so what's the biggest star then that we can get oh uh i think the biggest star is um ui scooty fun name

yeah fun name um it's bigger than say beetlejuice it's one of these big red super giant stars so this is not a normal star it's sort of towards the end of its life and what it's done is is swollen up to accommodate for the fact that it's running out of fuel essentially and i think i read somewhere that like if the sun was about the size of a football then ui scooty would be the size of the london eye oh right yeah it's pretty huge and are there any like really weird stars like ones that just completely break the mold yeah so one of the weirdest stars that every time i read something about it i'm like what on earth is going on what in the universe is going on here? It's Eta Carina.

So Eta Carina is a star. Well, we think it was one star. We think it's probably more like two or three stars, maybe. But this thing had what's called the Great Explosion in the 19th century that was recorded around the world as sort of brightening to the second brightest star in the sky and then fading again. So not visible with the naked eye, at least after the explosion. I think it is now. But it did this thing back in like the 17th century.

And it's sort of been weirdly pulsing ever since then. And like if you look at it through a telescope, a Hubble Space Telescope, it's this big cloud of stuff basically. And it's this very weird shape almost that I've seen people had to print it off in 3D to really understand you know what shape it truly was and what its structure actually was and it sort of looks like this big blown out structure almost like a like an egg timer almost on either side which we think was from this great explosion event and i think the leading hypothesis

right now is that it's was three stars that were orbiting each other one of them sort of had this weird event that caused it to swell, but then that disrupted all the orbits, and then maybe one of the smaller stars sort of fell into it, and the stars actually collided. And that's what that great explosion event was. But then, you know, stuff is still happening as well now where that star is massive and it's taking off material from the star that's orbiting it, and everything is just mad, basically.

And do we know why a star like that would then pulse so pulsing stars are actually quite common we see them a lot and sort of the best hypothesis we have for the minute is just the interaction of gravity with the energy given off by the fusion processes inside the star so essentially you've always got gravity pulling inwards and you've always got this energy from the fusion pushing outwards. And so in the sun, it's very nicely balanced. And so we don't get a lot of variability and a lot of changeability with the sun. But in some stars, it isn't very balanced.

It is quite unstable. And so essentially gravity wins for a little bit before then you kickstart more fusion reactions because it gets denser. And then they push it back out again. But then those fusion reactions die off because it's not dense enough and then gravity wins again and so it's a nice sort of like cyclical nature to the star and they're really quite common and they really can help us as well in terms of like figuring out distances and luminosities and all sorts. Robert Massey is still with us so we won't be looking at our sun that's a big no-no but what are some of the other things that we can look out for in our night sky well it's not something that's easy to see but i

certainly feel we should talk about it and there is a in addition to the regular moon we currently have what's called a mini moon a temporary moon in orbit around the earth now it's in a very chaotic orbit it's sort of moving around between the earth and the moon and it won't stay very long we think it arrived in 2017 it was discovered in mid-February and it'll probably leave by the end of April. And there are examples of this happening before. This one has the name of 2020 CD3. There is some suggestion it might be a space probe

that we've just forgotten about, that has come, well, not forgotten about, but didn't know exactly where it was that's coming to orbit. There is a precedent for that as well, which is when a mission, I think it was a mission to the outer solar system or to Mars anyway, it went past the Earth, it was picked up by asteroid detection systems, everybody got very excited. And then they realised it was actually

the space probe on its way further out. And I remember arguing with a journalist who was trying to persuade me it was either a disaster or a triumph. And I thought, well, it was sort of both really, you know, the system worked and at the same time, it was a bit embarrassing. But yeah, this thing is there, it does demonstrate the solar system. It's quite dynamic. Things come near the Earth quite often. It's only a few metres across, so that makes it pretty much impossible to see with a small telescope.

But it's a great thing to know it's there. However, in terms of stuff you can see, we're obviously moving into the spring and you've got the equinox, the time when night and day are roughly equal in length. And so for us, the transition to the spring and in the southern hemisphere, the transition into the autumn. Do you see anything particular that day?

No, not really. The sun's just at a point in the sky where it's passing from the southern to the northern hemisphere of the sky. But it does mark the progression into the spring and eventually into the summer. Now, things you want to look out for, though, there are a couple of things I think are really worth doing. And the first one of these, particularly if you have a camera or just a smartphone camera, again, I've been playing around with this over the last few weeks myself.

At the end of March, 28th, 29th of March, you'll have Venus and the moon close together in the sky. This is going to happen roughly every month while Venus is around. And you'll see a beautiful thin crescent moon. You can also see not just the crescent, but what looks like the night side of the moon lit up by the earth called the earth shine and you'll see the two of them together in a region of the sky with the hyades and pleiades clusters and they're quite easy to spot as well so actually i think it's a really good time if you've got a smartphone if you've got one with clip-on lenses if you've got a small telescope or even just a dslr with a decent telephoto you should actually take some great images and it would be really nice if people could email us

at podcast.ras.ac.uk. Nice. It would be fabulous to see that. The stabilisation on some of the new smartphones is incredible for night sky photography. I managed to snap a picture of Orion walking home in the day. Literally, didn't even stop. I saw this on your Twitter.

It was literally just lit up. It was amazing. And there was a giant street lamp there as well. Phone didn't care. Still got Orion. It amazes me that something that comes like thousands of light years that you can capture. I mean, obviously with our eyes is incredible, but something like that we have also developed in terms of a smartphone is incredible. My phone's probably not as good because I feel so frustrated when you see something that looks gorgeous in the night sky. Like, let me grab a photo. You're like, looks rubbish. I'll just remember this moment. To to be fair the moon is one of those hardest things to capture with your smartphone because it is so bright so i love this tiny thin crescent moon with venus it's one of my favorite things i call it a

toenail moon because it looks a bit like a toenail cutting and so thin but it looks gorgeous i always want to take a picture and it never works and you need one of these clip-on lenses that robert was talking about to really do that properly it's hard because you've got a real contrast. What you really want to get is the beauty of the earth's shine, the bit that looks darker, and to get a camera that will cope with really bright moon, which is almost as bright as the rocks you look at on Earth, and something which is getting on for as dim as the night sky,

that's really tough. But if you can do it, then the results are really, really stunning, and please send them to us. I'm going to get this again. Like Becky, I was playing with my smartphone doing the same thing. It is doable. If you've got a half-decent camera on a smartphone, it's not too hard to get something. Right.

Clip on lens. Got my phone. Off I go. Right. I'm going to. Well, maybe I'll be one of the people to bring in my shoddy picture. Like, please. Any picture of the night sky is beautiful, is it?

Yeah, definitely. Anything else that we should keep an eye out for? Well, the other thing to look out for towards the end of april is the lyrid meteor shower now this is one of the well-placed showers of the year meteors are basically bits of debris coming into the earth's atmosphere quite small you know sand grain size but they come in at such a high speed that the air around them gets super heated as they burn up and you see this streak of light now you ever seen a shooting star that's a meteor they typically they're only visible for half a second my experience is always you're out with somebody

they say there's a meteor by the time you turn your head it's gone so you do need to be looking up if you want to see them the peak of this is around the 21st 22nd of april and the expected activity may be 18 an hour or something like that not huge so you'd need to look out for quite a long time probably be patient if you want to do that. Obviously, you need a clear sky. And with this shower, it appears to come from the constellation of Lyra, which is a summer constellation. And what that means is that you're better off looking for it towards dawn or towards the last bit of the night when it's very high in the sky. But the meteors could be anywhere in the sky. Just get yourself away from streetlights if you can, because the other bonus of this is that the moon won't interfere either. Quite often with meteor showers, you have a bright moon and then it swamps the night sky you

don't see as many but this one is a really well placed one for that reason no moon around high up in the sky good from the northern hemisphere and again if you have a camera where you can sit there and look at an area of the sky with a long exposure then you should be able to try and capture some meteors and if you get those obviously do send them as images to us as well yeah it's funny that the really bright moon that sort of swamps the meteor showers i think is the only time that amateur astronomers really appreciate how annoying the moon is because if it's a professional astronomer if you want to use a telescope to observe like a really faint galaxy or something and you're like this would be the perfect time of the year to do it and this is

when i've been given the time except the moon just swamps the entire sky it can be really annoying so I feel like you know as much as we all love the moon and we love our new mini moon as well we also have to be a bit wary of times that it can get in the way absolutely that's it for this edition of the supermassive podcast we'll be back next month to explore the chaos our sun could cause to earth and hearing about the latest mission to visit our nearest star. If you've enjoyed this, then please don't forget to subscribe so that you never miss an episode. And don't forget to tweet us if you try some astronomy at home.

It's at Royal Astrosoc on Twitter, or email your questions to podcast at ras.ac.uk, and we'll try and cover them in a future episode. But until then, happy stargazing.