The Supermassive Podcast - 11: Radio Skies & Strange Signals

Episode Date: November 20, 2020

It’s about time we gave optical telescopes a break! This month, Izzie Clarke and Dr Becky Smethurst explore radio astronomy with Professor Tim O'Brien from the UK's Jodrell Bank Telescope and Professor Lisa Harvey-Smith, former project scientist for the Australian Square Kilometre Array. Plus, Robert Massey shares his top tips for stargazing at home and choosing the right telescope for you. Send you pictures and questions to [e-mail] or tweet @RoyalAstroSoc. Space Book Club Recommendations:  When Galaxies Collide - Lisa Harvey-Smith   Space: 10 Things You Should Know - Becky Smethurst  Moon: Art, Science, Culture - Robert Massey & Alex Loske No Shadow of a Doubt - Daniel Kennefick  How To Be An Astronaut and Other Space Jobs - Sheila Kanani The End of Everything (Astrophysically Speaking) - Katie Mack The Supermassive Podcast is a Boffin Media Production by Izzie Clarke and Richard Hollingham

I think I want to become a radio astronomer now. You know when people ask you is it worth going out for a meteor shower? I'm like yes. Does anything actually get in the way of these signals? I'm literally just detecting particles of light again that just happen to be radio waves. Hello, welcome to the Supermassive podcast from the Royal Astronomical Society. With me, science journalist Izzy Clark and astrophysicist Dr Becky Smethurst. Yeah, this month we're exploring space with radio astronomy. I

think it's about time we gave optical telescopes a little bit of a break. Yeah, definitely. So personally, I think radio astronomy is one of those topics that it does take a moment to wrap your head around it. definitely i agree that i think it's because we're so used to using radio waves in like everyday life to to transfer information right that we eventually hear as sound right so we use radio waves either am amplitude modulation or fm frequency modulation to transfer information right back and forth on you know your car radio or your kitchen radio whatever it is and yet here with radio astronomy we're talking about just detecting light in the

same way that you would with optical telescopes or x-ray telescopes or whatever it might be and it sort of takes a minute to just sort of flip your brain from going no no i'm not i'm not receiving information that i'm going to hear I'm literally just detecting particles of light again that just happen to be radio waves. Yeah, exactly. Well, over this episode, we'll hopefully understand what exactly is going on. But as always, Robert Massey, the Deputy Director of the Royal Astronomical Society joins us too. There are these impressive optical telescopes in stunning locations like Chile or Hawaii. And whilst it may not be as exotic, the UK's reputation for radio astronomy is pretty good, isn't it, Robert? It is. I mean, actually, it happens that the RAS called for the setup of a radio observatory in the UK as far back as the late 1940s, I think 1948. And part of the result of that was the

establishment of the really famous observatory at Jodrell Bank. And I know you've got Tim O'Brien on later on talking about that. It's really good. We've got Jodrell Bank, the headquarters of the Square Kilometre Away, Mullard Radio Observatory in Cambridge, where Jocelyn Bell discovered pulsars, you know, really great heritage. Jodrell Bank too, I think they did a huge number of things that gave them a high profile in early days, like detecting Sputnik 1. They grabbed the images from the Lunar Nine lander before the Soviets had released them to the world. And they tracked Apollo 11 as well. So it's really iconic. And I suppose we're good at it because the weather's not great for optical astronomy here. So we can do radio. Yeah, understatement of the year.

But the reason that I ended up picking optical astronomy is because of the amazing telescopes in chile and hawaii i was like should i go on field trips to manchester down the road cheshire is very nice becky i know i grew up around there but i was just a bit like i could go to hawaii if i became an optical astronomer yeah amazing robin anyway we'll catch up with you later in the show for some more stargazing. As Becky mentioned, radio waves are a type of electromagnetic radiation best known for their use in communication technologies like television, mobile, and, you know, surprise, surprise, radios. But we can also use these waves to explore our universe.

So how does radio astronomy actually work? I spoke with Professor Lisa Harvey-Smith from the University of New South Wales in Australia, who started with the basics. Unlike the name, you might think it's something to do with music or sound, but actually it's about looking at the invisible universe. looking at the invisible universe. And by that, I mean looking at the colors beyond light, the rainbow colors that we can see with our eyes, and actually looking at very different types of radiation from space that are essentially stretched out versions of light waves. And they can tell us really different things about the sky that we can't see.

So it's a bit of detective work. It's a bit esoteric and hard to imagine how it works, but it's good fun and a really useful tool for scientists. So what exactly is the benefit of using radio waves rather than other parts of the spectrum? Because we're so used to hearing about visible light and that side of things. hearing about, you know, visible light and that side of things. Well, definitely radio astronomy is not as pretty as optical astronomy, but it's very useful. So what we can see is the invisible, things that are not able to be seen because they're either hidden in dense, dusty regions of our galaxy. For example, things that I study like the birth of stars, it's all hidden inside a cloud.

The womb of star birth is this dense, dusty region. So we can see through those kind of regions and peer inside and really find out what's going on. And so why is it that you can do that with radio rather than other parts of the spectrum? Radio waves are much bigger. They're actually centimetres or millimetres or even metres in wavelength. So they're much larger. They can get through dust and gas that's hiding the light because the light is sort of scattered and absorbed by little particles. So in that that way it enables us to see a lot further in the universe and and to probe the history as well billions of years of history of our universe and and really write those history books i i think it's it's quite an odd concept or maybe that's

just for me but to wrap your head around because as you said at the beginning, we associate radio sort of with music, tuning into the radio, but you're effectively tuning telescopes to see the invisible. So how can you do that? How does it actually work? Well, there's a lot of technology out there that we use, but really it's quite simple. We get something that's made of a metal that conducts electricity, just like on an old fashioned radio, you had the antenna that you pull up and you'd point it around and try and get the best signal. So that's what we do. We get an antenna. Sometimes we put it on a big dish to collect lots of radiation. And you'll probably

know some of those dishes like the Lovell telescope at Jodrell Bank Observatory, for example, that's where I did my PhD studies, and other famous giant radio telescopes around the world. So we collect the radio waves in a big dish, essentially, it reflects off into a metal receiver, and that turns the radio waves into electricity. We put them down a little wire into a computer and Bob's your uncle, we make images of the sky in invisible radio waves. So we can actually tune those telescopes into different radio frequencies, into different stations. And one of those stations is hydrogen FM, for example example so we tune to 21 centimeters or 1400 megahertz

approximately and we get this amazing radio station which tells us where all the hydrogen gas is in the universe and with that we can see the galaxies and clouds of gas in space and we can also tune into other chemicals which helps us to understand the chemistry of space, which is fascinating. So just how different does the sky look through radio waves and radio astronomy? There's this beautiful image that I show when I do talks, and it actually shows the radio sky. It's very, very different from the sky that we see when we look up at nighttime. Instead of thousands of twinkling stars, we do see dots of light in radio. We do see dots of radio waves. But instead of stars, they're actually galaxies really far away. And these galaxies have supermassive black holes in the middle. These are huge black holes

that are millions of times more massive than our sun. And they're actually eating stars and ripping them apart and also eating gas. So they're kind of sucking in their meals and their victims. They're whirring around and all the gas is getting really really hot and emitting radio waves so this is one way we can study black holes and the evolution of galaxies very very far away so it's a fantastic tool really for that and am i right in thinking there was that amazing well picture but it's almost the shadow of the first ever black hole that was the event horizon telescope is that using all of the same technology that was the event horizon telescope is that using all of the same technology oh wow the event horizon telescope what a magnificent achievement oh i know it's just it's just incredible i mean i've i've worked in radio astronomy for more than 15 years and

i've used networks of radio telescopes spanning across the globe and giant supercomputers to synthesize the images together. But this was taken a step further. They've used higher radio frequencies to look for the signals of the black hole. It's such a technically difficult thing to make pictures. Firstly, you're making a picture of something very very distant very invisible and you've got the atmosphere to contend with so it's a very tricky thing to do and they've done an incredible job and I can't wait to see what they do next yeah absolutely now another thing I wanted to ask you about is something called the square kilometer array telescope which again is also a huge challenge the scale of these things sort of

blow my mind so for anyone that hasn't heard of that what's the basics of the square kilometer array telescope well we call it the ska short for something kind of awesome because it is going to be amazing and it's been an idea that astronomers have been talking about for 20 years, which is basically getting a bunch of radio telescopes around the world and joining them up electronically to measure radio waves from the universe and to do that in a way that's creating a telescope hundreds of times more sensitive than anything that we've created before. So it really is a telescope for planet Earth to talk to our history and to look to our future and to figure out if we're alone in the universe and to find out all the extreme physics of matter in space in laboratories far more distant and more powerful than we can imagine or create here on Earth. So it is is about 140 000 radio telescopes in western australia and a couple of hundred big dish telescopes in south africa so it's going to be these two different technologies complementary technologies to find out a bunch of stuff about

stars galaxies black holes, physics, the history of the universe, magnetic fields, you name it. But I think the most exciting thing potentially is the things that we're going to discover that we haven't even thought of yet. And that's what happened when Jocelyn Bell discovered pulsars. It was something we hadn't even imagined before. And those discoveries, like the fast radio bursts that we find when we stare into space, we still don't know what they are. And they're very, very powerful and very distant. And those kind of discoveries really take us to the edge of

understanding. And they really push the boundaries of physics and humanity's grasp on nature I think. Professor Lisa Harvey Smith I think I want to become a radio astronomer now after speaking with Lisa that was amazing. I mean I'm not surprised I mean Lisa is just a wonderful human being like I absolutely love her I loved her book um When Galaxies Collide it looks at what will happen to earth like when the Milky Way collides with Andromeda in whatever, five billion years time. And she just writes so, so beautifully. And she has all these kids books as well on space, which is so wonderfully written. She's just a fab person. I'm so glad we had her on. 100% agree. And we'll actually be coming back to books later in the show. Now, I didn't have time to ask Lisa about these things called fast radio bursts, but they've been in the news a fair amount recently.

So what exactly are they, Becky? Well, I wish I could tell you. It's still one of the big mysteries in physics. They're these millisecond bursts of radio waves that we detect from somewhere in the universe. So the first one was detected back in 2007 2007 actually in archive data that had been taken in 2002 so one of those things where we we kind of had the data to know about it sooner but we didn't i love this uh but since then we've seen quite a few of them in in sort of the hundreds right and we've seen a bit of a variety in their properties so some of them repeat some of them don't repeat if they do repeat it's it's very random it's not very periodic and regular. So they're a little bit confusing to people. But all the ones we detected previously were outside of the Milky Way. They were coming from other galaxies in our universe, except for the one that made the headlines very recently, that was coming from actually inside our Milky Way.

And do we have any idea what they could be? Well, there's lots of ideas floating around, obviously. Hundreds of hypotheses coming up. Here come the conspiracies. It's never aliens. But the one that we've detected in the Milky Way, this fast radio burst very recently this year that was making headlines. The reason it was making headlines is because we were able to sort of triangulate where this fast radio burst came from in the milky way and sort of pin it on a known magnetar now magnetar is a sort of a special type of neutron star with a very very high magnetic field it's a very exotic object and to be honest we don't really know a lot about magnetars either um but one of

the ideas that was kicking around for explaining you know how fast radio bursts could be produced was by a magnetar and the exciting thing was when people modeled this or simulated this this magnetar generating a fast radio burst in sort of the ways that they thought it might be possible you also generate an x-ray burst as well from the magnetar not just a fast radio burst and the reason that this FRB from a magnetar was so exciting was because they also detected an x-ray burst at the same time so it was sort of it's this detection is like a little extra sort of evidence towards the idea that magnetars could be responsible for fast radio bursts it's obviously only one piece of evidence though so there'll be lots of

follow-up work hopefully you might be able to pin more of these things on magnetars in the future and then maybe we can finally crack these fast radio bursts because it could be that magnetars maybe explain the ones that we only see once and never see again but what about the repeating things is that still to do with magnetars so there's still a lot left to do but it's at least hopeful that they're maybe not as mysterious as they used to be if we can pin them on magnetars somehow. Oh, okay, that's exciting. And when looking at the radio sky, does anything actually get in the way of the signals that astronomers have to, you know, take into consideration?

Oh, yeah, massively. I've seen so many observations that people have taken in the radio with various different telescopes where you're like, oh, that's cool, that looks really clear if you detected something there and that like that's a satellite passing overhead uh that's actually you know giving out a little bit of a blip of radio communications to the ground and you detect it and it's so much brighter than sort of whatever you're trying to detect from space that it just overwhelms everything it's sort of like the equivalent of a cosmic ray across any other sort of wavelength in astronomy so there is a huge interference from it we try and mitigate that as much as you

possibly can but the stuff that you can't even predict is going to happen there's a fantastic story from the parks observatory where they thought they detected something like these fast radio bursts and every day around about the same time sort of lunchtime ish like half 12 or something they were getting this little burst of radio waves like every single day not exactly at the same time just random enough to be off and they were like what is this have we detected some new phenomena and eventually they worked out that it was like the security guard on the front desk who at every every lunch time would like go and like heat up his lunch in the microwave but like instead of waiting for the microwave to finish he would open it early before the before the microwave had pinged and finished

and every time he opened the door while the microwave was still running it would just let out this tiny little burst the radio telescopes were sent to me to detect. And it's one of my favourite, favourite academic papers is them describing the most scientific way that they could come up with.

Yeah, I was like, oh, it's just Jeff heating up his rice. Now, the UK is well known for its radio astronomy and there's one telescope in particular that we had to mention the lovell telescope you'll find this at the jodrell bank observatory in cheshire and honestly you can't miss it because it's huge it's one of the biggest and most powerful radio telescopes in the world and sometimes i forget like how famous the level telescope and dodrell bank actually are because i grew up with them like coming from

lancashire and like always going and you can just see it for miles around too like i've seen it from winter hill in lancashire on a clear day for all my lancastrians out there that means something too and is he like i don't know but i almost I almost took it for granted right that it was there like every region has its Jodrell Bank. Well I was so excited to go for the first time I think the first time I went was for the first ever Blue Dot Festival and you really you're right you cannot miss it just looms over the horizon I was so excited when I saw it for the first time. It really is magnificent is it but yeah not every region has one it. It just looms over the horizon. I was so excited when I saw it for the first time. It really is magnificent, is it? But yeah, not every region has one. It really is just one of a kind. And so to tell us more, we've been speaking to Tim O'Brien, Associate Director

of the Jodrell Bank Observatory. And the first thing I wanted to ask him was just how big is this telescope? It is an amazing size. So it's 90 metres high. So for anybody who's more familiar with London, if you imagine sitting the Lovell telescope next to the Houses of Parliament, it's basically the top edge of it is exactly within about a metre, the same height as the top of the spike on the Big Ben clock tower. So it's a huge thing. It's 3,200 tonnes it weighs. The dish itself, the thing that collects the radial waves is 76 meters in diameter. 250 feet in old money as it was when it was made. So yeah, a huge thing. Yeah, it used to be known as the 250 feet telescope, right?

Its original name was the 250 foot telescope. Catchy. Yeah, imaginatively enough, yeah. Then it became the Mark I and then it was the mark 1a and then in 1987 it was named the lovell telescope after bernard lovell who who built it i mean the lovell telescope it's a fantastic name for it and you've touched on um our bernard bernard lovell already i guess we should sort of hear more about him like who was he and and why did he want to to build this telescope in cheshire yeah his interest you, it stemmed really from radar.

He worked in physics. He went to Bristol University and did a PhD there. Then he went to Manchester and was working on cosmic rays. So these high energy particles that arrive from outer space. He was working on that before the war. Then he went off, dragged off like many scientists were to work in the war. And he developed a airborne radar for tracking U-boats and things like that and for mapping the land for night bombing raids.

And then at the end of the war, he thought, oh, well, can I use this radar for something scientific? So he got some radar kit and he thought, what I'll do is I'll send up these radio waves, send them up into the sky. And what I'll do is I'll get echoes back from the trails that cosmic rays leave in the atmosphere. So as these charged particles from outer space

crash through the atmosphere, they leave a trail of ionised gas behind them, and that would reflect the radio waves. So that's what he started. He was totally swamped by electrical interference, radio interference from the trams in Manchester at the time. So he thought, oh, I need to get out of Manchester. Where can I go? And the university had these botany grounds down at this place called Jodrell. And they said, you've got permission to be there

for two weeks. And he never left. And we're still there now. But why did he want to set up something that is this big? I think it's an interesting story because he sort of started with this idea of studying cosmic rays because that's what he was already interested in. They did get echoes back immediately as soon as he switched the kit on, actually 75 years ago this year, so in early December of 1945. But they weren't from cosmic rays, they were from meteors, so meteor trails, sort of sand grain-sized things

burning up in the atmosphere. He realised that while he'd been doing these calculations during the war as to how to do this work, he'd made a mistake in his calculations. Oh, I've been there. And actually the signal... And his excuse was that they would be machine-gunned at the time. OK, I don't have that excuse.

I don't like that one, Becky. It's probably a good excuse. But he was basically a factor of a few thousand out. So he would never have detected cosmic ray because with the little instrument that he had, the old Army radar. So he needed to build a bigger instrument. And that was what led him to build,

actually, what was then the world's largest telescope, which was a transit telescope, a fixed dish, was what they built first of all in the late 1940s. And then when they started using that, they realised that actually it was useful for picking up radio waves from deep space. So they were mapping, they detected the Andromeda galaxy and the remnant of Tycho's supernova.

They detected for the first time anybody had seen it for 400 years. And they thought, actually, this is quite useful. We need one like this, a big thing that we can steer. And that was where the idea for the Lovell telescope came from. I've heard before about how the whole observatory has its roots in World War II with Lovell really inspired by that. But was any of the tech sort of repurposed? Yeah, I mean, they certainly, they used to go round in a van

and drive around the country sort of piling old electronic hardware into the back of the van because it was all, you know, sort of Those gear racks were actually recycled from the gun turrets, the 15-inch gun turrets of two World War I battleships, and they're still there. So it still tips today on World War I battleship technology. That is so cool. It's such a history. It's incredible, isn't it? And to know that it's still in use today and it's still all working all working fine what is level used for now is it used for similar things still or does it still have such like a wide ranging like interest that it can be used for so when they

originally designed it they had a you know as we would do these days with any new instrument we would we write a science case uh for for why someone should give us the money to build this telescope and you can look down the list of things in the science case and why someone should give us the money to build this telescope. And you can look down the list of things in the science case, and some of them we recognise. Some of them would be things like studying the gas in other galaxies, our Milky Way and other galaxies, and that's still something we do. Some of them not so much, so they had a lot of stuff about the aurora. But in fact, now, most of what the telescope does was totally undreamt of when the telescope was designed. Of course, it's been upgraded many times over the years,

and it's far more powerful than it was when it was constructed. But still, the basic structure, this big parabolic dish that turns and points 20 points in the sky, that's still the same thing it always was. That was Professor Tim O'Brien, Associate Director of Jodrell Bank Observatory. This is the Supermassive podcast from the Royal Astronomical Society with me, astrophysicist Dr Becky Smethurst and with science journalist Izzy Clark. Earlier we mentioned

Lisa's book but I genuinely think we should start a space book club because one of us is a published author it's not me it's me congratulations okay so Becky tell us about your book what's it all about yeah so it's called space 10 things you should know and it's essentially about the 10 things that I think are the biggest ideas in astronomy right now that you know anyone interested in space from your complete newbie to your old hat you know we should just you should all just know about you know everything from does life exist out there you know looking at it from sort of like a maths perspective and working out all the numbers in terms of like the probability that life exists out there you know how we know dark matter exists as well and then also the astrophysics equivalent of the chicken or the egg which i'll leave as a little bit of a tenterhook to pull everyone in

have you got any favorite parts of it i think the fact that i managed to get so many references in this book i don't think everyone reading will pick up on but there's like there's a mean girls reference in there there's a a reference to the Christmas film, the Santa Claus as well. And there's a Moana reference. There's so many references in there that I just think so many different people will get. I just love it.

I don't know how I managed to convince my editor to let me do this, but they did. Oh my God, that's so great. And Robert, can I bring you in here as well? Because you're also a published author i mean i'm really starting to feel left out here no pressure here is it have you got any good astronomy book recommendations yeah absolutely i mean apart that the one we wrote i will bring my colleague alexander loser on the moon is is

good obviously you'd expect me to mention that uh but um i was thinking in line with some of the stuff we were talking about earlier in the year about einstein's theory of relativity i strongly recommend no shadow of a doubt by daniel kenefic and he talks through the whole story of how the work was done how that amazing discovery of the bending of starlight was made and also challenges all the doubters that were around at the time and since then and picks out the you know some really unsavory stuff that was directed towards einstein's work because he was german and because he was jewish so it's a really really interesting story and it uh you know it turns out right in the end obviously but i do

recommend it also to give you an insight into just how hard science is particularly imagine you're making discoveries like this just with photographic plates it's it's a great read and if you're making discoveries like this just with photographic plates so it's it's a great read and if you're interested in books for children then my colleague sheila canani has an excellent space one called how to be an astronaut and other space jobs which is a a good guide for all of us i think i mean i might get that yeah it's great for you you need it right how to be an astronaut so you can become best friends with samantha cristopher etty right this is yeah i mean you already are i also love um, you've seen Katie Mack's book that's come out recently as well, The End of Everything, astrophysically speaking. Like it's such a good title, first of all.

Yeah, it's on my list. It's all about how, you know, the universe might end and all the different ways that we think it could happen, like in terms of cosmology as well, like going off the science. And Katie's just such a wonderful writer I absolutely loved it I can't I can't recommend it enough and that concludes our first ever book club thank you everyone for attending now if anyone else has recommendations definitely let us know you can tweet at royal astrosoc or email us at podcast at ras.ac.uk so let's get

back to this month's topic where we're chatting all things radio astronomy so we've got some questions Robert and Becky that we need your help with um Becky can you take this one from Johnny the sailor and he says how do you focus a radio telescope not the big dishes but the antenna arrays like the one Justin Belbanel used to discover pulsars. So focus is a bit of a weird word here because I mean we're not focusing in the same respect as you know you would focus a camera and turn a little sort of wheel to get the best focus because I mean we're essentially focused to infinity right because the objects that we're observing are so so far away that we don't ever have to adjust a focus as such right. I think what he's referring to is necessarily like with a big optical telescope, you know,

you have this big dish that brings in the light and brings it all to one specific place where the receiver is. Right. And then that's the same for, you know, the big radio dishes as well. Right. The light is all brought to a single place. Whereas with the antenna, you've got multiple of them. So I think what Johnny meant was that, you know, how do you make a single image out of these big antenna arrays?

And so this is actually something that's called interferometry. So it's a little bit hard to get your head around a little bit, but what you can think of it is that you have a distance between all of these antenna in these big arrays right and we know what that distance is and so there will be an ever so slight you know fractions and fractions of a second delay between radio light arriving at one antenna compared to the other antenna right and sometimes the these antenna can actually be moved on big grids around in circles or along tracks and so we can change those distances and so we can essentially get different perspectives on whatever we're observing.

But sometimes we just use the actual rotation of the earth to do this, to get a different perspective on an object. And so knowing the distances between these antenna and sort of watching for these little time delays in the arrival is essentially how you can then reconstruct all these different perspectives that you get of an object into a single image of what a source looks like. And so if that sounds incredibly difficult,

that's because it is. It in fact won Martin Ryle a Nobel Prize back in the 70s for actually figuring all of that out. And it is an incredible, incredible tool that we can use to do this, because it means that we can resolve so many smaller things by using these huge arrays sometimes that are the size of an entire planet like we have with the event horizon telescope as well so an incredibly powerful tool yeah no biggie okay so simon longley wants to know robert how do you determine signal distances that is whether a new signal has come from 20 or 200 light years away? Well, the answer is it's much the same in some ways that you do with optical telescopes. So you

can make various assumptions about how far away things are from the nature of the signal and its intensity. But the nice thing about radio observatories, when they're as big as the Earth, like the Event Horizon Telescope, is you can use something called parallax, where you look at the source six months apart. In other words, when the Earth is on different sides of the sun. And that Event Horizon Telescope is you can use something called parallax, where you look at the source six months apart, in other words, when the Earth is on different sides of the sun. And that tiny shift in perspective, because these radio telescopes, the Earth-sized ones, have such high resolution, you can detect a tiny shift in the position of the source compared with the background and get a pretty accurate handle on the distance. Now, it doesn't work very well if

things are, say, in distant galaxies, but for stuff in the Milky Way, it's really good. So that's one of the techniques that radio astronomers use. It's not that different to what optical astronomers do as well. But this is, as Becky was describing, it's hard to go through all the details of this, but that's the basic principle. Right. And similarly, like to optical as well,

you can take a spectrum with a radio telescope too. And the specific line that they like to target is the 21 centimeter emission from hydrogen, right? And so similar to how you see emission from elements in the optical get red shifted with distance, the same thing can happen for the 21 centimeter line and we can get at distances that way. But that requires like a radio telescope that can give you a spectrum, which is not something we had immediately and so when radio astronomy first started

and they were detecting you know quasars and everything and there was no optical counterpart to them because their optical telescopes weren't good enough yet to be able to spot whatever this thing was coming from this is where we didn't know that they were at such great distances because you know as Robert said sort of the intensity of the light or what using the parallax isn't possible when they're in such distant distant galaxies so if we've been able to know that sooner get at what actually the distances these things were we maybe galaxy evolution would be much further on I don't know right thanks for clearing that one up and Becky Buzzer wants to know how would one get started in radio astronomy from home that's a great question

because i mean i've never done any radio astronomy from home i don't know about robert robert be able to uh to chip in here but you definitely can get started it's not something you can do you know with your kitchen radio or the car radio because as i said there are these frequencies set aside for that kind of communication so you probably never be able to detect anything except for i don't know your local radio station um but you can get started. There is a great, there's a load of great resources online. So for example, the Society for Amateur Radio Astronomers is great. It's got so many resources, so many links. You know, I've seen people online building their own radio telescopes, maybe around a hundred quid or so, you know, with the right kit, really fairly basic. And they've

been able to detect, you know, the emission from this hydrogen in the spiral arms of the Milky Way, and they can detect the rotation of the Milky Way, which is fantastic for a little bit of at home kit, right? So I mean, I've never done it myself. I remember doing a little bit of radio astronomy in the lab undergrad with like, yeah, again, what looked like something that, you know, I dug up from a landfill or something, this old little box what about you robert have you ever done anything like this i've never done it no i've seen people presenting at conferences i've seen kit on sale but i've never indulged myself i've used when i was a postgraduate i used georgia bank data but that's not quite the same thing at all but you're

right there are people with these uh you know antennae in their backyards and they're able at least to detect emission from the sun and the brighter sources, and I guess, monitor how things change over time there too. So I suppose, given we're in the UK, you know, what we were saying earlier on, if the weather's bad here, then it does at least give you that option if you can't see the stars with your eyes. Yeah, and still some connection to what's out there in the universe, I guess. Well, that's radio astronomy from home. But what else can we see in the night sky this month, Robert? Well, this is a nice time of year to be looking at the stars, although it's getting colder. Of course, we have longer nights, the longest nights during December. So you have

plenty of opportunities to look up. Things I point out, I think definitely I have to mention the Geminids meteor shower on the 13th to the 14th of December, because quietly it's one of the strongest displays of the year. You might see as many as 70 meteors an hour if you're lucky, if you're in a dark place. They're quite slow, they're quite bright, and they often have a distinct yellow or other color as well. I remember I've only seen them a couple of times because the weather's not that reliable at this time of year, but I always try to look out. Yeah, they're my favorite, I think, my favorite meteor shower. You know, when people ask you, is it worth going out for a meteor shower like is it going to be that good i'm like yes for the gemini it's a hundred percent yes definitely if you've got a clear sky

do it you know even if you only get up for an hour in the school hours and have a look and this year there's no moon in the sky so it's a it's a really good chance if you're in a dark place um you know we will start to see the winter stars later on as well. So you see things like Taurus, the bull, and the Hyades and the Pleiades star clusters, which again connects to general relativity I mentioned briefly earlier. But another event to look to is on the 21st of December. So we might mention this in the next podcast as well, which is when Jupiter and Saturn are in something called a great conjunction. Now, in this case, the two planets will appear to be the closest they've

been together since the 17th century just six odd minutes apart so if you have a small telescope you know you could look through that you could see two planets it's almost like that sort of science fiction for you of you know planets looking so close together so i was thinking we've got to encourage people to take some photos of this we know how many talented astrophotographers there are we'd really like to see those yeah absolutely reminder what date is that uh 21st of december after sunset so they'll be quite low in the sky from the uk and you don't have very long to spot them but it's it's got to be worth a look um if it's clear then then get out and have a look definitely i've got i've got binoculars on my christmas list maybe i have to like ask about

the christmas if those can come a bit early so i can see the great conjunction of saturn and jupiter yeah and speaking of that you know people are looking probably with holidays around the corner potentially looking to buy telescopes so what functionalities should people be considering before they're buying telescopes well i it's a it's a you know a great question is we often get asked it i don't want to recommend brands because there are just so many good manufacturers but i think talk to a specialist if you can talk to a dedicated telescope shop talk to an amateur astronomy society because they'll give you good advice the general advice is i will say to people start with a pair of binoculars if you don't have them because you can just pick them up use them they're straightforward

you can see quite a lot you know craters on the moon galaxies nebulae quite easily with those and they're affordable and you can use them for other things but if you want to get a telescope then it really depends where you are you know whether you've got a car whether you plan to be going out to the city to look at things or or not and how much tech you like because you can get quite small lens telescopes refractors that are quite easy to set up and they'll show you like because you can get quite small lens telescopes refractors that are quite easy to set up and they'll show you things like saturn's rings but if you want to see more you need a bigger telescope and obviously that the budget goes up with that as well the thing about that though is the bigger the telescope gets clearly the harder it is to hoik around so you need

you know if you if you need something you're going to have to load into the back of a big car that's probably not a great choice so i would i would say something that you're is small enough for you to be able to move around and use easily if you don't live somewhere really dark something like a you know a small refractor is great for starters if you know a bit more than a newtonian reflector is good value if you've got a bit more money you get these mixtures of lens and mirror telescopes called catadioptrics and they they're sold by various companies and they're stubby, but they're really, really good optics and they'll give you good views of everything, but they are quite a lot more money. Generally though, start straightforward

and work up through the levels of these things. Because even if you go on to buy a bigger telescope as you get more developed, you're probably still going to keep the small one and the binoculars and because they're easier to do things like take on take them on holiday with you yeah i always say like how much how much do you want to faff yeah whatever you get right because binoculars are literally just grab them out the drawer go put them back 10 minutes later you might be done uh if you want to something a bit bigger that you can see something else with but with the minimal amount of faff i always think like a dobsonian telescope is great for that because it's literally just plonk it on the ground and point it at the sky there's no calibration no setup or anything like that um whereas then if you want to take

the next step i think it's something like what you've got izzy right which is is sort of the refract is it refracted yeah yeah yeah and it's that kind of has a little bit of setup you know and so it's not as quick but you'll probably be able to see even deeper again and probably much more stable than like a drop zone you know something like that so exactly but for me as well like I live in London I don't have a garden but I live really near a park so I knew that I needed something that okay yes there is a bit more setup but at the same time I do have that option of you know sort of taking apart carrying it around to the park which is fine um so for me it was literally transport was also a huge factor in that i think we should also mention too that yeah i mean those are good points another thing that occurs to me is you want something

that's stable as well think about the mounting if you've got a really wobbly mount and a telescope it's terrible so you know if you buy a telescope or you're given one with a wobbly mount it's worth thinking about trying to upgrade that because that'll make a huge difference too yeah definitely it's all these things that you've got to consider isn't it like budget whether you want it transportable like how much setup do you want like have a good research in terms of like what you know that is good for you and your family and whatever and will suit you guys best because there's not just like a one telescope catches all that we can recommend yeah yeah if only yeah but to be fair i love it so just you know do your research but it is great once it arrives well i think that's it for this month um we'll be ramping things up next time with some high energy astrophysics your favorite becky

and tweet us if you try some astronomy at home we'd love to see some photos 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 next time happy stargazing