Instant Genius - How we look at the Universe with a radio

Episode Date: March 13, 2026

There’s an entire cosmos hidden from our human eyes. The only way to see it is by looking at the Universe with a radio. We talk to Dr Emma Chapman about how she uses radio telescopes to reveal the cosmic mysteries of the Universe. Learn more about your ad choices. Visit podcastchoices.com/adchoices

No one goes to Hank's for his spreadsheets. They go for a darn good pizza. Lately, though, the shop's been quiet. So Hank decides to bring back the $1 slice. He asks Copilot in Microsoft Excel to look at his sales and costs to help him see if he can afford it. Co-pilot shows Hank where the money's going and which little extras make the dollar slice work.

Now, Hank has a line out the door. Hank makes the pizza. Co-Pilot handles the spreadsheets. Learn more at M365Copilot.com slash work. When you need to build up your team to handle the growing chaos at work, use Indeed sponsored jobs. It gives your job posts the boost it needs to be seen and helps reach people with the right skills, certifications, and more. Spend less time searching and more time actually interviewing candidates who check all your boxes. Listeners of this show will get a $75-sponsored

job credit at Indeed.com slash podcast. That's Indeed.com slash podcast. Terms and conditions apply. Need a hiring hero? This is a job for Indeed sponsored jobs. You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost! Or you could book a stay with Hilton.

Welcome to your oceanfront room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for the stay.

This podcast is sponsored by name, audio and focal. Streaming has made music more accessible than ever, but true listening is about more than ease. It's about quality. British audio experts name audio, alongside French acoustic specialist focal, combine handcrafted tradition with cutting-edge innovation and high-end materials, delivering digital precision with analogue warmth,

so you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. Hello, and welcome to Instant Genius, a bite-sized masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Ezi Pearson, commissioning editor at BBC Science Focus. In today's episode, I'm talking to astrophysicist Dr Emma Chapman from the University of Nottingham. When most of us look up at the night sky, we can see pin-priced.

of light shining down from the stars scattered in the universe around us. But our eyes aren't seen the whole story. There is an entire cosmos hidden from our human eyes. It only becomes visible when viewed not with visible light, but radio waves. As a radio astronomer, Emma peers into this secret side of the universe, hoping to reveal its mysteries which she talks about in her latest book, Radio Universe. Hello Emma, and welcome to Instant Genius. Hi, Izzy.

I suppose one of the very first questions that we should be asking is what actually are radio waves and how do you use them to look at the universe? Well, we're really familiar with radio in daily life. You might not even realize that you are almost certainly carrying a radio telescope in your pocket. And that's your mobile phone in a way. So the way that we communicate messages on Earth is using radio waves. That's why we have a radio. if you still have a radio in your kitchen, but mostly it's now miniaturized into your phone, little tiny antennas, constantly talking to each other, constantly talking to satellites, downloading your favourite podcast, BBC Science Focus, or other ones do exist. Other podcasts are also available. And so what radio waves are are just a form of light.

So lights we're very familiar with. It's we turn on the light to see a room. that's because it's what our eyes have been evolved to see, this visible light. But that's just a really tiny section of a much wider spectrum, which we call the electromagnetic spectrum. Now, visible light is this little rainbow, kind of in the middle. You can kind of think of it like that. But it's surrounded by different other categories of light that you're really familiar

with. So UV light, for example, which has the property that it's really good at sterilizing germs, for example. You've got microwaves which are really good at heating up food. They are just the perfect energy to excite your jacket potato into a yummy meal. But really down the spectrum, right at the end, lowest energy, longest wavelength, we've got the radio waves. And their property is that they're able to travel really long distances without losing much information, basically. So they're really good communicators. And that's why we use it to broadcast from antennas with all our radio stations and indeed Wi-Fi and everything like that. So when it comes to how we just transfer that to looking

at the universe, it is simply looking up. We just begin to look up at the universe and we begin to listen to what the universe is telling us in radio waves using the same kind of antennas that we gather radio waves on Earth, and we communicate with the universe as well. We can create radar dishes to send radio waves out, bounce off stuff, come back, find out about what is up there. So we use radio waves in summary just in the same way that we use visible light without eyes and telescopes like Hubble, for example, but we just need to build a different kind of telescope to utilize a different part of the electromagnetic spectrum, that long wavelength radio. I love that idea of we're communicating with the universe.

And what exactly is it that the universe is trying to communicate to us? What kind of observations can you do with radio waves that you can't do with something like visible light? Oh, what can't you do? This is what led me to write this book, is that my background is cosmology in the first stars, and that's where I use it. But then I started to read about the history of radio astronomy and I suddenly realized that there were all these different parts of astronomy that I had thought visible light telescopes had kind of really led the discoveries and I suddenly found that very quietly under the surface radio astronomy had been in almost every single field that you can think of doing its work, getting on with it, not running for the glory, not needing clean rooms and rockets. needing screwdrivers and a good pair of boots, and they just did it over decades.

And so I was reading about pulsars and how they were discovered, these spinning neutron stars, which we can talk about in more detail later, looking at how we took the first image of a black hole using radio waves or going further into history. Did you know we didn't even really know we lived in the spiral galaxy until we had radio telescopes? So you can think, yeah, we might live in a disk,

of stars, sure. But actually, there's not much information if you're just looking at those pinpricks of light, whereas you turn on a radio telescope. What that does is able to see between the stars. It's able to see the gas, which makes up a huge amount of galaxy, and it's able to map out the spiral arms of the galaxy. And that was the first confirmation that we had, that we lived in a spiral galaxy, which I find absolutely incredible. And the reason that we can do that is exactly the same property on Earth that radio waves are really good at traveling long distances and keeping their information. And the reason, the way they do that is that they are able to kind of evade dust. They're not bothered by water vapor. If it's raining, who cares?

If it's sunny, doesn't matter. Just carry on. Whereas, you know, you're an astronomy, you've got on astronomy background. If you try and look at Orion's nebula at midday, can't see anything. It's not going to happen. Whereas if you turn on a radio telescope, the sun is really quiet. And you can see the galaxy. It's just astonishing to me that there's this hidden universe that even astronomers aren't aware of how much we owe to that longest wavelength. But now, obviously, if radio waves aren't visible light, that means they're in there. visible. So how do we go about translating what comes into your telescope into something that we can see and understand? Observing radio light is really similar to the way we observe optical light.

Light comes into our eyes. It causes like an electric stimulation and our brain translates it such that we can then see an image. Now when it comes to radio light, yeah, our eyes can't do that, but our telescopes act as the translation device. This radio wave comes in that we can't see. see, but it stimulates electrically this antenna. And the way that it does that, we can kind of assign it a color that we can see. It's a bit like paint by numbers. So paint by numbers, when you look at it, it's just a canvas with ones, two, three, fours, five. But if you say, hey, one is red, hey, three is purple. What we do is say, okay, one meter wavelength is red. Three meter wavelength is purple. Then when your radio light comes in, you could actually build up an image that we're using

that translated like those translation colors, paint by numbers and get the same kind of images that we're used to seeing in optical light, but just translated into something we can see. The thing that always gets me as well is radio astronomy is actually a very young discipline. You know, people have been doing visible light astronomy since we evolved eyes, but radio astronomy has only been about the last hundred years or so. But when it comes to looking with these radio waves, What is it that we're actually looking at? What is the sort of bit of astronomy that it's focusing in on? It will depend on what it is you're looking at.

So you're right, just to say it is a very young field. It's about 75 years since kind of the first big radio telescope that is still around today. Can I just say? Jodrell Bank. Still around today. And yeah, the first radio wave from space was detected in 1933 compared to, as you say, when humans evolves, if you're going to look up optical astronomy. So we are young science, but we've managed to do some incredible things. What it's looking at, it's looking at the

same things that we're used to talking about day in and day out and astronomy, but forgive the fun, in a different light, at a different angle, if you will. So for example, one of its major uses is mapping out the gas, as I've previously mentioned about the spiral arms of the galaxy. the universe is predominantly made of hydrogen gas. It might sound really boring because it's not a gorgeous nebula and it's not a lovely star, but gas is what is the universe and it tells you about the structure of the universe. And that hydrogen atom produces a very specific wavelength of light. It's 21 centimetres in wavelength. It's radio.

So when we point our telescopes up, we can map out, like I said, the spiral arms and work out where we live. But you can even extend that and you can actually look at other galaxies and you can look at how they're rotating. And if you know about dark matter, the only reason we know that there's this weird, mysterious substance called dark matter is because we measure the rotation of galaxies, the stars orbiting in the galaxies. But a galaxy, where the stars stop, there's way more galaxy past that and that's gas. So what radio waves allow us to do actually measure the rotation of the gas in spiral galaxies, way out, almost up to twice, two, three times as far out as the stars, and really probe the dark matter halo. So, A, it's

enabling to do the same thing, but just a little bit further in a different way. And the same if I'll give you a solar system example, because I've mentioned that it's able to kind of glide through clouds were able to look at Venus, but whereas if you look at Venus in the optical, you see its clouds. That's all it is. You see a hundred percent cloud cover. You look in the radio, you send a radio wave down, you let it bounce off the surface of Venus. It comes back in about the time it takes to have a cup of tea. You go get, put the kettle on, get a cup of tea, come back. You've got your radar signals back and you've mapped the surface of Venus. And this blows my mind. You can see the volcanoes of Venus using radio waves. When I was reading through the book,

that was one of the things that surprised me a little is how much radio observation there is done in the solar system, particularly involving radar. So what other ways can we look at our solar system with radio waves? Yeah, so just to mention, because I haven't really said it, we're used to using radar, but just because anybody says it but doesn't really know what it means, what radar is, is when you send a radio wave out, you let it reflect off your target, you wait for it to come back, and how that radio wave has changed in intensity, in wavelength, in polarisation, so like the direction that the wave is wriggling in, tells you a huge amount about not only where the object is, but how fast it's moving and what it's made of. So for example, radar is absolutely crucial for

mapping any dangerous-looking asteroids. So if we've got an asteroid that we're a bit worried about, optical's great to follow it, but it can only do it every, let's say, 12 hours because of the daytime. And if the asteroid is coming from the direction of the sun, oh dear, you can't see it. Whereas radio, you can spread radio waves out into the solar system. And then you can listen to see what reflections come back. and you could map the surface of these asteroids to incredible quality.

They rendered a model of one using radio waves sent from this Aricebo radio telescope in Puerto Rico, and they mapped it to the same quality as when the actual probe got there several years later and was able to take optical visible light mapping. Yep, so you've got that kind of radar, and you could apply that to the moon. You could look for lava tubes and caves on both the moon and. and Mars, which are vital. If you want your Artemis astronauts to land on the moon, and then there's a massive solar flare, they need to know where to run.

And until you've got enclosure or a habitat, which has radiation shielding, you're going to have to use what the land has given you, which is caves. And they are really hard to see from optical mapping. And astronauts don't have the time to do a geological survey. They really don't. No. But what radar does is it just bathes the moon or the section of Mars that you're looking at with radio waves. And those radio waves can dig just a little deeper.

They can dig like about a meter through the surface of these planets where the optical, you know, just caught on. And it can dig through and then work out from the reflections, oh, I found a cave. and you can work out the under surface structure, which is fascinating. And if you've got time for one more, which I find absolutely mind-blok, ice on mercury, man. Ice on Mercury. The closest planet to the sun has ice. Ice on Mercury, okay? I mean, sometimes if there's a lulling conversation to anybody, I'll just be like,

ice on Mercury. Did you know that? Like, these are people that I barely know. as well. But everybody from like my hairdresser to my, you know, colleagues are always flawed by this unless they work in the field. And this is what I find fascinating about radio astronomy is that we really keep it quiet sometimes what we've done.

And so what they managed to do was they did the same thing. They irradiated mercury with radio waves, took a few minutes to get there, came back. And there were patches of really, really high reflective. material on these maps. And they worked it out and it could only be water ice in the permanently shadowed craters of Mercury. And that was confirmed a few years later with a flyby. It's bonkers sometimes the things that you find when you look out there, especially when you start looking in a way that you've never looked before. And of course, it's not just the solar system that we're looking at. We're also, radio astronomers are also looking out into the wider universe.

So how is radio useful? You've already talked about galaxies, but how else is radio useful looking at the wider universe? This is definitely when we transition from using radar, which is like an active communication form of astronomy, if you will. That kind of peters out around Saturn. They have managed to make a radar observation of Saturn, which is so underwhelming, but oh my God, also so amazing

because the planet disappears and you just see the rings. Because that's the reflective part. That's the shiny bit. But anyway, that's year limit. And it's not really scientifically useful at that point. So we switch and we no longer try and communicate. We just simply listen. We put on our listening ears and we see what the universe has got to tell us.

Now, I've talked to you about kind of the hydrogen that can map dark matter halos and can map the spiral arms. I mean, pulsars, I suppose, are the one that I should start with because pulsars are the one that won the Nobel Prize for radio astronomy. Justin Belbenel in Cambridge, she created this radio array in the 1960s, and they started hearing like a pulse, a repetitive pulse, couldn't work out what it was. For a moment, joked that it might be aliens, but ultimately determined that actually this was the first evidence of a previously only theoretical thing called a neutron star. And if this neutron star is spinning very, very fast, it's like a lighthouse. There are beams of radio, coming out of the poles, and as it spins and that beam crosses the path of Earth, we get a pulse.

And so this was a fantastic discovery. And people are using this today with the new square kilometer array telescope. They're going to look at thousands of pulsars, and they're going to use them as a timing system to measure the passage of gravitational waves through the universe, which I just find astonishing. You think you just need like. Virgo to do gravitational wave stuff, but... Nope. Vigo and Virgo are two very large gravitational wave detectors in Italy and the US, I believe. Yes, yes, that's correct, yeah.

And one of the things with gravitational wave detectors is they need to be very, very big. And so using pulsars, which are, you know, hundreds if not thousands of light years apart, that kind of makes sense. It's just a really, again, an interesting way of looking at a problem. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank.

It's peak pollination season, and my business is scaling fast. To keep the nectar flowing, I need a phone plan with top priority data speeds. That's why I chose GoogleFi wireless. My connections stay strong even when the hive was buzzing. Plus, unlimited plans started 35. plans started $35 a month. Now that's a deal that doesn't stay. Explore GoogleFi Wireless plans today. Plus taxes and government fees. GoogleFi Wireless is not subject to data traffic deprioritization during times of high network usage. This podcast is sponsored by Name, Audio,

and Focal. With over 100 years of combined expertise, Name and Focal have been bringing music to listeners just as the artist intended. Since day one, this mantra has shaped every and in high-fi design, technology and acoustic engineering, balancing craftsmanship and tradition with pioneering thinking. Name Audio pushes cutting-edge technology to ensure digital precision whilst sustaining Pratt, pace, rhythm and timing, the elusive quality that makes music feel alive and gives it emotional texture. Today, in partnership with French acoustic specialist's focal, name audio creates systems that deliver exceptional sound. and unforgettable listening experiences at home.

Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. In terms of what radio waves can tell us about the wider universe, you've got everything from gravitational waves. The pulsars are just interesting in general, and you can't see most neutron stars without that radio light. So you just wouldn't be able to know about them. But there's also looking back in time,

which is my speciality. So all astronomy is looking back in time because of the finite speed of light. So when we send people to the moon, there's going to be about 1.5 second delay on any messages going back and forth when you go to Mars. The teenagers I talk to are fascinated by the idea

that they're not going to be able to do gaming with Earth because there'll be a four-minute lag at least. It would be difficult. Yeah. And so you're seeing your friends getting, as it was four minutes in the past. So when we look at light that has traveled long distances, we are looking further and further back in time. Now, optical can only get so far. And that's when

JWST comes in, because the infrared light, you can get a little bit further. But the radio light enables you to go right back, not only to the first galaxies and the first stars, about 200 million years after Big Bang, but even further back into what we call the cosmic dark ages, which is when there was only hydrogen, that exact same gas that still pervades our Milky Way today. So radio waves allow us, it's the only way, I will even make it stronger, it is the only way that we can probe those earliest times. Why is it exactly that visible light doesn't travel that far? What's making it go away. Yeah, no, so it's not going away.

It's doing something called red shifting. So if you have a very bright, let's do a thought experiment. If we've got a very bright first galaxy or something like that, or UV, you know, really bright going very high energy in the UV part of the spectrum, which is the higher energy part above visible, that's emitting loads of UV light. But as the universe is expanding, the further something is, the further it's expanding away, if you will, the more that light gets, we can think of it as stretched, the more that light we see it as redder and redder.

Now, it's the same effect as when an ice cream van or fire engine goes past you, and you hear the siren as it's going away from you, it goes, Neen-no, need, no, ne'o, ne'o, so it goes to a lower pitch. And so when you've got galaxies moving away from you, the further they are, the lower the pitch we hear, the light or are the same. see the light. And so when you've got something that is, let's say, 12 billion years after the Big Bang, so only about a billion years ago, let's go the other way, if you've got something about a billion years ago, yes, fine, Hubble can still see it. It's been red shifted,

but it's still within the visible spectrum. So what was blue might be slightly less blue. If you go to something like six billion years ago, now you're seeing a really red galaxy. If you go to 12 billion years ago, oh dear, Hubble can't see a darn thing, but it's now into the infrared part of the spectrum and JWST can see it, go back to the cosmic dark ages, and all you've got is radio. Everything at that point has been redshifted out. Now, you did mention there when you were talking about pulsars, they thought for a while it might be aliens.

I believe it was little green men or LGMs it was jokingly referred to as. What ways is radio waves, are we actively using radio waves to try and find alien life? I'm so excited about this question. Not that the listeners can see, but I am wearing a T-shirt, which has the first ever message that we sent to alien intelligence using a radio telescope in Puerto Rico. It's called the Drake message. And if you can imagine space invaders and like if you ever played space invaders, that pixelated thing, it looks exactly the same. but it's like a pixelated human and a pixelated map of where the Earth is, and it's very cute. And this is just one way that we have tried to communicate with aliens over the years,

because SETI, which is the search for extraterrestrial intelligence, has always been led by radio astronomers. And it all comes down to that reason, communication. We are trying to communicate with extraterrestrial beings on other planets in our galaxy, and to communicate, you need radio waves because it can get. through cloud cover on different planets and it can travel really long distances. Also, we can kind of guess what they might send because they're going to be sending something that they know we will have developed the technology to receive. So a really good way to start

is looking, for example, at that 21 centimetre wavelength where all of the hydrogen in the universe is, but not just looking for kind of what you normally see, listening for something that sounds really weird. And what that means is repetitive. Not much in nature is repetitive. And not much is repetitive to the point of, let's say, encoding the digits of pie, which will be the same on any planet. So what we're looking for is very simply a radio signal from a different star system, but a radio signal that we can't explain. It doesn't have to be that it says in English, hello, we come in peace. That's very unlikely. But what it would do is it would have some kind of property like it would be repeating the digits of pie. It would be repeating prime numbers.

And it would be talking in mathematics, but via radio. So we've got antennas doing that all over earth. It's something I do with my master's students. It's a lot of fun and it's a very popular project. But we found nothing yet. But just have to keep looking. And the excitement, I actually, I find SETI researchers fascinating. So I dabble in it, but it's not my main thing. When I talk to people who are day in day out doing this, they are just a very different kind of researcher. They are thick-skinned for start because they can deal with misplaced skepticism. But they are also, there's a peace to them. They leave silences and they're very kind of like content because they've realized they've come to terms with the fact that all of these, this work, quite possibly might not get, we might not get a signal until past their lifetime. It could be tomorrow, but it could also be in 200 years. It all depends on whether we're listening in the right direction at the right time. And it's just a numbers game. It definitely takes a certain kind of mindset to be able to do something like that.

I would like to take a minute to actually look at radio telescopes themselves. What do radio telescopes actually look like? Are they the same as an optical telescope? Radio telescopes are really diverse. So with an optical telescope, even the youngest child can bring to mind this idea of a tube. One end you look in, one end has a lens at the other end to magnify. And of course, we've got all these smart telescopes now, which you don't look at, you look at your phone, but it's the same kind of idea. Radio telescopes look far more like that rusting, unloved satellite dish. on the side of your house, which you will almost certainly have, and you will almost certainly not

have used since maybe the 2000s, something like that, whenever streaming came in. Radio telescopes are the antenna that you had on your car in the 1990s, and you had to pull up in order to get the best signal. So radio telescopes, because they cover such a large part of the electromagnetic spectrum, from a few centimetres to metres to tens to a hundred, of kilometres, you have to build telescopes that look actually quite different in order to capture all of those different kinds of light. So, for example, if you're doing something, let's think, where you're trying to pick up the repetitions of pulsars, then you might build something like the Lovell Telescope at Georgia Bank, which is about 300-foot dish made of lots of metal,

and they're able to steer it on wheels very slowly, and they're able to point at different objects. If you're looking at something more like the cosmic dawn, the first stars like I do, then actually we need a bigger telescope. And the wonderful thing about radio is that we can build kind of, they are, they're not fake, but they're like proxy telescopes because radio waves, wavelengths is so large. It doesn't care how shiny the mirror is, if you will. So what we could do is we can put antennas that are like a meter apart. And to the radio waves, it still looks like a really short.

shiny mirror. So what we've done is if you could just imagine kind of the kind of antenna you might have had on your old radio a little bit more to it than that, there might be some kind of cross bits of metal and everything. But at the end of the day, we've put about 1,300 of those very simple looking antennas all over the Netherlands and for a telescope called Lofar, join them all up. And across kilometers, they have built this telescope that effectively is kilometers wide and it's able to gather radio light right back into the era of the first stars. So the thing about radio telescopes is they look really underwhelming sometimes. Like, I remember when I was told I was going to be a radio astronomer and I was bitterly

disappointed because I thought I was going to get to go like observing in Tenerife and Hawaii. They're like, no, you need to get a really good pair of boots, a really good waterproof coat and you'll be going to the Netherlands once a year for the rest of your life. I'm like, right. But oh my God, I fell in love with them. And that's the other reason I wrote this book is because I'm such a nerd now that every time I travel, I look up if there's a local radio telescope or a deep space network communications one.

And I just email them. I'm like, can I come see your telescope, please? And they're always dead thrilled. So I've seen some incredible sights. I've been to the jungle of Puerto Rico and seen a dish, which is 0.3 kilometers wide nestled in the jungle called Aricebo, which was unbelievable. And yeah, I love even the little tiny ones that don't look like much because they're not even moving. They're allowing the sky to drift over them.

They're allowing the whole sky. And so they just patiently watch night after night, year after year, because they last so much longer than space-based telescopes. They don't need fuel. repair them. And there's a patience and a piece. And when you're there and you know what they're actually looking at, you know that they're gathering light from black holes. It's like a form of meditation for me now. Actually going to these places. That does sound amazing. I will say though, a kilometre-sized telescope does seem a little bit excessive. Is there any reason why they're so big? It comes down to resolution. So it's the same kind of resolution equation, which determines

how big your eight-inch celestial telescope needs to be in order to see kind of like the moons of Jupiter or something like that. And that equation involves both how big your lens or your mirror or your dish is, but also what your wave length is. Now, if you're observing at radio, you need a bigger dish to reach the same resolution as optical, if that makes sense. But we don't just reach the same resolution as optical. Because the engineering of it allows us to basically build a radio telescope as big as we want, we can get to much finer resolution than optical. And that's why we were able to take the images of the gas falling into the black hole

at the center of our Milky Way and at the center of Sagittarius A-Star with a resolution which is equivalent to being able to see a bagel on the moon, which you cannot do with optical telescopes. And I love that you can fix them. And you can keep extending them as well.

Like with JWST, James Webb Space Telescope, the space-based infrared telescope. I love it. But it's not going to last forever because it has to have cryogenic cooling systems that are going to run out. whereas we're still working with the Lovell Telescope. You just go put on a new bolt and a new liquor paint

and you upgrade the computational side of it, which is absolutely state of the art. That is the state of the art part that we work with. But I've talked to people whose grandparents built the dish they work on. Keeping it in the family then. It is a lot easier when you don't have to worry about mirrors and things like that. It is. You just have to worry about scorpions and,

kangaroos and we had a heart-stopping moment when we thought a group of, I think it was either otters or beavers. I never get, I can't remember which one's in Europe, but whichever one, the whole family of them were advancing on loafer and they were protected. And we knew that if they got to our cables, that was our science over until they decided to move on. And so we have animal watch a lot with these telescopes. You know, compared to all these clean rooms and fancy rocket launches, it's quite different. They don't have to worry about that on the Hubble. Beaver's moving into the telescope. Though another problem that a lot of astronomers do have is light pollution,

which has been a growing problem for optical astronomers. Is there a similar issue for radio astronomers? Because there is lots of radio waves bouncing around all over the place. Yes, absolutely. And this is actually how radio astronomy was discovered as a field, was that Karl Jansky in 1933 heard a hiss in his headphones. His job was to make transatlantic calls as clear as possible, he heard a hiss. Eventually, I've cut the story short, he worked out this hiss was for radio waves

from the centre of our Milky Way. And that started the idea of wait, the universe can communicate in radio waves, but we also have to reverse that because we were able to hear these radio waves on a communication system is the other way around two. So when we have radio telescopes, we can hear the transatlantic calls and we can hear mobile phone calls. So if you turn your mobile phone on near a radio telescope, it will wipe out the signal from the galaxy. So we have to have very clear rules about no mobile phones on site. We have federally enforced quiet zones, we call them, around, for example, the Green Bank telescope in West Virginia.

So that's legally protected. If you live within kilometers of that telescope, you're not allowed Wi-Fi. You're not allowed certain types of microwave even, or automatic doors, which use radio, radar. So it's very, very, very careful. And it is always getting worse. And the big elephant in the room, of course, is Starlink and its colleagues. So we were kind of okay.

We were kind of managing. Because the radio noise on Earth was all coming from kind of Earth. So we could tell where it was coming from. Our skies were still fairly clear. We could look day or night. Lovely. Stalin came out and it's competitors. and honestly, I can't even put a number on it,

but it would not be a foolish number to say tens of percent up to most of your data is now thrown away because of these streaks across the sky, the same as you see with optical, but just radio light. And they, unfortunately, day or night, they leak radiation in protected radio wave bands, and they say, well, we've tried our best, but this is just unintentional leakage. But there's so much of it that even if it's unintentional, even if it's small, it's catastrophic. What I will say is that now these companies are beginning to speak to the radio astronomy community, they're actually clever ways of circumventing it.

So Starlink is able, its constellations, what they do, these satellites, they beam radio waves down. And for a great reason, right, to give everybody the opportunity to have high-speed internet access. I'm for that. But what they had started to do is communicate with the radio astronomers to get their schedules so that when those satellites are flying over that telescope at that time, and they know it's observing, the Starlink's supposedly will turn their beams away. So when they fly over, they will look the other way. Now, whether that has actually been implemented, whether it's enough remains to be seen.

But one of the ways that we could possibly get around radio wave pollution is what people have done with optical telescopes, which is put them in space. Particularly, quite often hear people talking about building a radio telescope on the moon. is that now that people are a bit more interested in the moon again, is that something that's actually looking like it might happen one day? How feasible is that? Oh, absolutely. The first steps have already been taken. We've already launched a radio satellite with an antenna

which has measured how quiet it is around the moon. That first stage has gone up. As much as I love Earth-based radio astronomy, because it's so, again, forgive the pub, down to Earth, in terms of astronomy compared to all like the glitz and glamour of the space missions. I love the fact you can go get a cup of tea and have a walk while it's observing. But yes, we cannot get past the fact that it's now very, very, very noisy down here. The idea is to go to the far side of the moon and that the moon itself naturally blocks out

all of that radio frequency interference that was bothering you on Earth. It's not perfect anymore. Unfortunately, there are so many satellites now around the moon for all of these different space missions, it is no longer radio quiet and it is getting very noisy, very quickly. So it's not perfect. I'm saying that first because, oh my God, am I excited? The idea, like the idea of going to the moon, like that's amazing. And the idea they're coming up with because obviously, like, we're used to having to walk up with a screwdriver. Like, I've literally got bolt here from one of my radio telescopes. Like, you just have to be really nut, sorry, Not from one of my radio tasks.

You have to be really used to like hands on and getting in there. It's a very different thinking set for us. So I'll just tell you about three of the ideas briefly. So the idea is to autonomously land radio antennas on the far side of the moon and either have them roll out so that your antennas are actually a strip of wire. So it's actually rolling out from this lander, which just sounds amazing. The other one I love is that you land, let's say, 50 lunar rovers, each with an antenna on its back. And then you send signals to say, hey guys, can you dance in this way, please, and make a nice spiral?

Actually, now can you dance this way and make a nice cross, and it'll enable me to see that pulsar a little bit more or something like that. So the idea of it on the far side of the moon where no one can see them, you've just got this fleet of moon rovers. having a little dance in order to see different parts of the universe. Love it. And then the last one I am super excited about is using a crater as a dish. So usually what you have is you have a dish on earth, like just a big, big metal dish, which reflects any incoming radio light and focuses it on what we call the receiver, which is an antenna which takes in all of that radio light and takes it off to your computers. The idea on the moon is that we would use a crater, which is a lovely natural thing, and we would autonomously land three or four rovers, and that they would

stretch out bits of wire meeting in the centre and dropping that antenna so that any radio waves falling into that crater from the universe would bounce back up onto our radio antenna and tell us all about the world. And yeah, and I absolutely love that. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Dr Emma Chapman. To discover more about the topics we've just discussed, check out their latest book, Radio Universe, available from the 12th of March. If you like what you just heard, then please consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then why not check out our YouTube channel at Science Focus?

The current issue of BBC Science Focus is out now. Pick up a copy wherever you buy your favourite magazines or download us on your app store of choice. You can also find us on Apple News or online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analogue warmth.

Alongside French acoustic specialist vocal, Name creates high-end audio systems, combining innovation with craftsmanship, so you can listen to music, just as the artist intended. Discover more at nameaudio.com. Relax and let Ralph's delivery handle your grocery shopping this week. We start with only the freshest items,

then review your list and carefully choose each one. Then we pack it all up and deliver it in as little as 30 minutes, so you can feel confident it's what you ordered. Fresh groceries, your way, with Ralph's delivery and pickup. And right now, you can save $20 on your first delivery or pickup order. Ralph's, fresh for everyone.