Lunar Magnetism & Cosmic Signals: Insights into Moon Mysteries and Radio Discoveries | Space...

[00:00:00] [SPEAKER_01] Hi there. Thanks for joining us. This is another episode of Space Nuts. We talk astronomy and space science and window dressing and you name it. We will talk about it. And my name, did I say my name? My name is Andrew Dunkley, your host. Good to have your company. On today's episode, we're going to look at lunar magnetism. Did the moon ever have a magnetic field? Or is there something else that had happened to it in the past?

[00:00:29] [SPEAKER_01] They think they've got it figured out. Maybe. We're going to talk about a not alien radio signal. Windows in spacecraft have come of age and we'll tell you all about that. I think the early astronauts insisted, I want a window. I want a window. And they got one. Well, now it's very high tech. And a very interesting photograph, a chance photo that turned out to be rather special. We'll tell you all about it on this episode of Space Nuts.

[00:00:59] [SPEAKER_01] Space Nuts.

[00:00:59] [SPEAKER_03] 15 seconds. Guidance is internal. 10, 9. Ignition sequence start. Space Nuts. 5, 4, 3, 2. 1, 2, 3, 4, 5, 5, 4, 3, 2, 1. Space Nuts. Astronauts report. It feels good.

[00:01:16] [SPEAKER_01] And with us again to sort out all of that is Professor Fred Watson, astronomer at large. Hello, Fred. Hello, Andrew. Good to see you again. How's your week of golf gone? Painful. Painful. My back is protesting. In fact, I played my fourth round today to wrap up 72 holes of golf over five days. We had a rest day on Wednesday. I think it should have another name like Why You Bothering Day.

[00:01:46] [SPEAKER_01] And I tweaked my back. Strangely enough, I was just bending over to adjust the ball. And I wasn't quite balanced. So when I moved my leg to correct my balance, my lower back went, no, can't do that. And I'm going to hurt you. And yeah, spent the rest of the round fighting that. Oh, dear.

[00:02:06] [SPEAKER_01] But I had a pretty good week. I came second in the 36 hole event, which was terrific. And I had three nearest the pins. That's the closest shot to the hole on a par three where the ball stays on the green. So yeah. So yeah, I had a good week. I hit the ball quite well. I was very, very pleased. Not as pleased as if I could have won it, but you know, that's golf. That's golf. How's your week been?

[00:02:34] [SPEAKER_02] It's been a long time since I saw you. Well, yes. Still nursing the new knee. And the milestone this week was getting out on the bike again for the first time, which is great because it's a good way of extending your range of motion on the knee, which is all about straightening it.

[00:02:57] [SPEAKER_02] The straightening is what's called the extension, which has to be zero degrees. And as it is on the knee that I had done in 2020, it took a while to get there, but I did.

[00:03:10] [SPEAKER_02] At the moment, the new knee is standing at two degrees, but getting on the bike actually lets you stretch it. And so I'm hoping that will pull it down so that when my physiotherapist from Doncaster in Yorkshire measures it next week, she might find there's a big difference down from the two degrees that it was this week.

[00:03:34] [SPEAKER_01] What you don't want to hear when you're riding a bike after knee surgery is the clatter of titanium on tar. You don't want to hear that.

[00:03:43] [SPEAKER_02] That will be bad. Yes. Yes. The physiotherapist tells a horror story that's not too far from that. Oh, really? She said, I can tell you this now. I can tell you this now because your wound has healed up completely. I won't relate it. No, but I'm imagining. But it was a horror story. Yeah, yeah. Pretty horrible. Anyway, never mind.

[00:04:07] [SPEAKER_01] Nasty. Nasty. All right. We should get down to our stories. And this first story takes us to the moon. The moon's been in the news a lot lately for all sorts of different reasons. The lack of water was, I think, the last thing we talked about. But this story is actually focusing on the magnetic field. Now, Earth's got a magnetic field. It's generated by all the goop inside that's doing whatever the goop does.

[00:04:37] [SPEAKER_01] And that magnetic field protects us from, you know, being burnt alive or whatever. Now, the question is, did the moon ever have a magnetic field? If it did, how was it generated? And so on and so forth. So what's the situation?

[00:04:57] [SPEAKER_02] So, yes, the bottom line is the moon doesn't really have much of a magnetic field now. It's got traces of magnetism. And interestingly, those traces of magnetism tend to correspond with what was the buzzword back in the 1960s, the mass cons,

[00:05:19] [SPEAKER_02] the mass concentrations underneath the surface of the moon, which were discovered when orbiting spacecraft were first sent to the moon in advance of the Apollo missions. So that's a sort of pointer, the fact that where you've got these mass concentrations under the surface, and you detect those, by the way, by the fact that they pull down on an orbiting spacecraft. And so its trajectory changes slightly.

[00:05:47] [SPEAKER_02] So that's what basically lets you plot them. And in fact, you can see maps of the mass cons these days because we've had many orbiting spacecraft that have charted them. But the magnetism tends to concentrate there. And as I said, that's the first clue. So this is some research that's been done by scientists at actually Einstein's old university, ETH Zurich.

[00:06:13] [SPEAKER_02] And they have basically looked at some of the evidence from perhaps more carefully, the evidence from the gravitational samples, the fact that these can now be mapped with great accuracy. So what they have done, this is published now, I think it might be still being referee, but I think it's published.

[00:06:39] [SPEAKER_02] They've looked at a region, it's actually on the far side of the moon. It's called Dewar, D-E-W-A-R, which is the name of a very famous Scotch whiskey, as probably people would know. But it's also the name of something on the moon, probably came from the same origin. I don't know. Anyway, it turns out that this Dewar region has one of the strongest, what they call a magnetic field anomaly,

[00:07:08] [SPEAKER_02] which means basically there's a magnetic field there because the moon generally doesn't have a strong magnetic field. So one of the authors remarks that the Dewar region is a genuine stroke of luck. One of the strongest magnetic field anomalies on the far side of the moon and a distinct gravity anomaly coincide spatially there. They're in the same place.

[00:07:32] [SPEAKER_02] So it means that, you know, the region of the moon's surface has rocks that are both more strongly magnetized and more dense, a denser concentration of mass than elsewhere.

[00:07:50] [SPEAKER_02] And the trick now is to sort of analyze both of these aspects, the fact that you've got a mass concentration and a magnetic field anomaly. Another comment from one of the authors, says the gravity data give us insight into the density and thus into the material beneath the surface.

[00:08:13] [SPEAKER_02] Where the magnetic field and gravity signals coincide, it's possible to combine the two and attribute the anomaly to a specific geological structure. This is precisely the opportunity that Dewar offered. And so that's what they've done. They've basically built a model that actually mimics both the gravity concentration, the increased density and the magnetic field.

[00:08:43] [SPEAKER_02] And so what the outcome is, is that somewhere below the surface of the moon in this region, there's a body of rock quite big, 60 kilometers wide, going down something like nine kilometers, much denser than its surrounding crustal region and also strongly magnetized.

[00:09:07] [SPEAKER_02] And so what they have concluded is that this is basically solidified magma, something that goes back to when the moon was a much more molten object than it is now with a viscous mantle. And what they're saying is that because they think this structure is 4.2 billion years old, it's nearly as old as the moon is.

[00:09:33] [SPEAKER_02] What you can do is, well, I'll read again from the comments from the author. Because we know how much iron is present in such a rock body, we can estimate the minimum strength the magnetic field must have had as the magma cooled slowly. That's a very important finding. We found that the magnetic field on the moon at that time was very likely stronger than 10 micro tesla.

[00:10:02] [SPEAKER_02] On Earth today, the magnetic field strength is around 50 micro tesla. So what they're saying is that this supports the notion that the moon had a primordial magnetic field. It had magnetism when it was a young object rather than an alternative explanation for the magnetism, which is that it could have been caused locally. You know, this magnetism being caused here and there on the moon's surface, maybe by impact.

[00:10:31] [SPEAKER_02] The effect of the impact would be to increase the magnetism. And so the outcome is that that's not likely to be the source of the magnetism. It's likely to have been a primordial magnetic field.

[00:10:46] [SPEAKER_01] So they're suggesting that it's a leftover effect. So the moon did have an internally generated magnetic field. As it's cooled down and solidified, this is just a residual leftover magnetic anomaly. Exactly that.

[00:11:04] [SPEAKER_02] So they say this means, yes, the moon was magnetic at one point. There's a little sort of subsidiary study, though, that I think is quite interesting. We haven't talked about them, I don't think, Andrew, but there are features on the surface of the moon which are called lunar swirls.

[00:11:23] [SPEAKER_02] They're sort of regions of brighter material which form in swirls rather than, you know, the craters and mountains that we're used to seeing. But what they have noticed in their work is that wherever there's a swirl, there's one of these magnetic anomalies. And it turns out that the region they've been looking at, this Dewar region, has a lunar swirl.

[00:11:51] [SPEAKER_02] And so, you know, the struggle is now to explain this. Why would you have these curious features on the moon's surface which are linked with magnetism? And they're basically suggesting that you only get the swirls when you are in an area where the magnetic field,

[00:12:17] [SPEAKER_02] the field lines, the lights of force are actually horizontally at the surface because that's the case with this Dua lunar swirl. And so what they're thinking is that maybe the horizontal field actually modifies the solar wind. Perhaps it deflects it. Perhaps it protects the surface from weathering by the solar wind and you get this brighter region. Isn't that interesting?

[00:12:45] [SPEAKER_02] Yeah, isn't it an interesting piece of work? It's got so many facets to it. I think this is one of the most interesting pieces of lunar research that we've seen for a while.

[00:12:55] [SPEAKER_01] Mm-hmm. And, yeah, adds another element to our growing knowledge of what the moon is all about. And, yeah, I think we're kind of lucky to have it. It's, I mean, it's good for life on Earth. I don't know if we'd exist without it, would we?

[00:13:15] [SPEAKER_02] That's right. Probably not. You know, the Earth's magnetic field almost certainly is what's allowed us to evolve from microbes into the...

[00:13:25] Yeah.

[00:13:25] [SPEAKER_01] You know, when you sit down and look at all the data and start to really analyse it, there is so much that exists that we need to exist, if that makes any sense. You know, if one or two of those things never happened, we wouldn't have happened either. It just blows your mind that all of this stuff that enabled life to evolve to this level on Earth had to be just right. And, yeah, it's got to be a rarity.

[00:13:55] [SPEAKER_02] That's right. And I think that's the thinking among astrobiologists. Everything, you know, basically everything has come right on Earth for an intelligent species to evolve, and it's not necessarily the case elsewhere.

[00:14:10] [SPEAKER_01] Yeah. Interesting. If you'd like to read about the Moon's historical magnetic field, you can do so at phys.org. That's P-H-Y-S dot org. Or you can read the study in Science Advances. This is Space Nuts. Andrew Dunkley here with Professor Fred Watson.

[00:14:31] [SPEAKER_03] Zero G and I feel fine.

[00:14:33] [SPEAKER_01] Space Nuts. Our next story, Fred, is a not alien signal. But it's fascinating because it is a signal, a radio signal coming from, you know, they usually think that these things come from stars. But this one, they've actually been able to say, hang on a minute, we think. In fact, we are sure this one's coming from a planet. And of course, that gets the tongues wagging. Oh, it's a planet. It must be aliens. But it's not. It's something else. Something we all know about. It is. Really?

[00:15:04] [SPEAKER_02] Correct. That's absolutely right. And yes, the reason why this is a big story is that these are radio signals that come from an exoplanet rather than, you know, a gas cloud in space or a star or a radio galaxy, all the other things that emit radio waves. This is actually from a planet.

[00:15:24] [SPEAKER_02] And the way it's been proved that it comes from a planet is really one of the most interesting parts of the story, as well as how we know it's there. It was all the selfies that came in with it. Yeah, the selfies did it. So this is, it's a gas giant. It is called Beta Pictoris B. It's an exoplanet that has been known for many years.

[00:15:52] [SPEAKER_02] It's the fact that it's called Beta Pictoris B means it's the first discovered planet around a star called Beta Pictoris, which I think is about 50, 54, if I remember rightly, light years away. 64, there you go. So it's a relatively nearby star.

[00:16:09] [SPEAKER_02] So the other thing that I find interesting about this is it uses, the data that have led to this discovery have come from Meerkat, the radio telescope, which is similar to the Australian Square Kilometer Ray Pathfinder in Western Australia. Meerkat is its sort of equivalent in the Haikaru region of South Africa and a very, very effective telescope doing some fantastic stuff.

[00:16:39] [SPEAKER_02] And it's been used actually by scientists at the Centre for Astrophysics in the Smithsonian, Harvard and Smithsonian. They've used this Meerkat to make very, very accurate measurements of the position of this radio noise. And the way they've done it is a way that, to some extent, we've used before. I'm not sure whether you and I have ever spoken about it.

[00:17:06] [SPEAKER_02] When you're measuring the position of objects in space, and I mean in two dimensions now, I'm talking about the direction that the radiation comes from. What you have to do is to calibrate it. You need to know where the sort of zero point is. So you need background objects that don't change their position to do the relative measurements.

[00:17:33] [SPEAKER_02] And those background objects are things that are far, far more distant than 64 light years. Their distances are measured in billions of light years, and they are quasars. Quasars are very bright in radio waves. And perhaps especially, and this is what allows you to do this, they are effectively point sources. They're a single point of radio waves. Very, very compact objects. And they're at great distances.

[00:18:02] [SPEAKER_02] So that lets you build a framework, almost like a map. You can map these quasars and then look at your foreground object and relate its position very accurately by the fact that the quasars don't change their position in space because they're so far away. And that's how they've done it.

[00:18:23] [SPEAKER_02] That's how they've worked out that these radio signals come not from the star itself, Beta Pictoris, but from Beta Pictoris B, this gas giant that's in orbit around it. And the thing you alluded to, right, sorry, go ahead.

[00:18:40] [SPEAKER_01] Well, I was just going to let you reveal it.

[00:18:44] [SPEAKER_02] And the source is? It's northern and southern lights on the planet. It's the aurorae, which we know are radio noisy auroral displays. They are on our own planet. You can detect aurorae by radio signals. I prefer to go and stand underneath them in the far northern Arctic in winter. And then you see these things in all their glory. But they do emit radio signals as well.

[00:19:13] [SPEAKER_02] And that's basically how these signals came to be. So it's a big triumph. It's the first time that we've proved that aurorae exist on other planets, in other solar systems. We know they exist on all the gas giants have in our solar system. They all have aurorae. The Earth does. Mars occasionally does. But this is just saying that wherever you've got a star with a planet going around it, you've probably got them as well.

[00:19:41] [SPEAKER_02] All you need is a star that's giving out charged particles, high-energy particles, subatomic particles, and a planet with an atmosphere. These are the ingredients you've got there because the high-energy particles essentially excite the atmosphere into beaming out light and beaming out radio signals.

[00:20:31] [SPEAKER_01] Simple as that. And you're with Andrew Dunkley and Professor Fred Watson.

[00:20:38] [SPEAKER_00] The crew of Artemis II now bound for the moon. Humanity's next great voyage begins.

[00:20:44] [SPEAKER_03] Space nuts.

[00:20:45] [SPEAKER_01] Now, Fred, from the extraordinary magnetism on the moon and aurorae signals from an exoplanet to windows. Windows in spaceships. You know, it doesn't sound all that exciting. But in the early days of the space race when the United States and the Soviet Union were trying to beat each other senseless to get to the moon,

[00:21:12] [SPEAKER_01] the early astronauts, those very brave souls, insisted that they had to have a window, as far as I remember. And they got it. Of course, they've come of age now. They've done some amazing things with windows in spacecraft. And it's in the news again.

[00:21:31] [SPEAKER_02] Yes, that's right. And partly in the news for the reasons that you've mentioned, that astronauts themselves have always been very keen on having windows. As you would, if you're going to sit, you know, 100 kilometres above the Earth's surface, hurtling around at seven or eight kilometres per second, you're definitely going to want to watch the view as it goes past.

[00:21:55] [SPEAKER_01] I would say so. What was it like up there? I don't know. I was looking at a piece of plywood.

[00:22:02] [SPEAKER_02] Couldn't see anything. So even certainly the first manned or crewed spacecraft in the NASA's human spaceflight program, which was Mercury. Mercury had a tiny little window. It's just a few inches in diameter, almost a porthole. And it wasn't much bigger in the Gemini spacecraft either. They had forward pointing windows, which were sort of scalloped out of the shape of the nose cone.

[00:22:32] [SPEAKER_02] And Apollo had forward pointing windows as well, which they needed, of course, by then, as they did with Gemini. And the reason why they're forward pointing is that that's where the docking ports are. You need to be able to, you know, see where your spacecraft is going if it's going to dock with another spacecraft. And the docking port is always in the narrow part, in the nose. So, yeah, that's – that windows became essential at that point.

[00:22:58] [SPEAKER_01] And Yuri Gagarin. Yuri Gagarin had a window as well.

[00:23:01] [SPEAKER_02] I thought he did. I was going to muse on that, but I thought that was right, that he had a window too. It's kind of – the window to be all windows, of course, is the cupola. The cupola, I should call it, give it its proper name. It's on the International Space Station.

[00:23:24] [SPEAKER_02] It has – I think it's seven, it might be nine panels of glass, which – it's like a bay window. Yeah. Which – I'm looking at a photo of it now, yes. Yeah. How many windows has it got? Is it seven?

[00:23:40] [SPEAKER_01] One, two, three – probably about eight, eight or nine. Yeah. Because there's one directly above as well. So, it'd be nine, I think.

[00:23:51] [SPEAKER_02] There's the front window. Nine's what I guessed as well. And I think the astronauts on the International Space Station spend quite a lot of time in that enclosure. Not just because it lets you see the various components of the space station and watch progress, you know, when there are extravehicular – or when there is extravehicular activity taking place. They're important from that point of view.

[00:24:18] [SPEAKER_02] But they're also important to watch the Earth going by. And we've seen so many great photos and videos that have been taken through the cupola window. So, that's the – essentially the, you know, the high point of window design on a spacecraft. But we've also got – Six windows. Is it? It's all.

[00:24:43] [SPEAKER_01] It's described as a trap-and-wittle arrangement. Okay. Yeah, six.

[00:24:48] [SPEAKER_02] Yeah. All right. Maybe there's some blank ports on the other side from where I'm looking. Never mind. I was just going to mention that both Virgin Galactic with their space plane and Blue Origin with their space plane, which are now – well, certainly Blue Origin is no longer being used because they're concentrating their efforts on Artemis. But they have got big windows as well. And, in fact, Blue Origin were really quite big.

[00:25:15] [SPEAKER_02] They were almost like bay windows around the whole spacecraft, a conical spacecraft, again, carried up to suborbital heights, about 100 kilometers on a rocket. So, the – I mean, the story here is, yes, windows are important, but are they safe? Ah, yes.

[00:25:38] [SPEAKER_02] There's – you know, there's an analysis that window – glass is a – as one of the analysts working on this says, glass is a brittle material. It breaks. That's what it likes to do. But it's also beautifully transparent.

[00:25:55] [SPEAKER_02] And so, it's basically – I think what they're saying with all this is it is a balancing act between glass being safe and you wanting to have as much real estate in terms of visible or transparency as possible.

[00:26:20] [SPEAKER_02] So, the bottom line, I think, is that windows are a worry. Yeah. You would need to have some way of evacuating or isolating the region where there's a window in order to protect astronauts.

[00:26:40] [SPEAKER_02] I mean, in the early days, the Apollo – sorry, the Gemini and the Mercury capsules, if there'd been a fracture, they'd have been into their spacesuits pretty damn quick. Whereas now, you all evacuate that chamber and shut the door. That would be what would happen. I don't think it ever has happened. I don't think there's ever been a broken window. I might be wrong with that, but that might be one we can check with AI.

[00:27:08] [SPEAKER_02] But the bottom line here is, are acrylics a better choice than glass? Because it's a more stable material, you know, something like perspex.

[00:27:22] [SPEAKER_01] Yeah.

[00:27:22] [SPEAKER_02] Not as good to look through, though. Probably not. That's right. And there might be other issues with acrylics in that regard.

[00:27:33] [SPEAKER_01] Yeah. Okay. Well, watch this space. Boom, boom. But it's – Through the window. Yeah. It's an interesting problem. This wouldn't be the same kind of glass you'd use in a house or an office block, though, would it? It'd be pretty highly specialized.

[00:27:50] [SPEAKER_02] Yeah. It might be more like what you've got in your car. You know, toughened somehow in a way that would – if they were going to fracture, they'd do it safely. Rather than – the last thing you'd want is shards of glass floating around in zero gravity. You know, imagine a sharp bit of glass going in front of your face if you're in orbit with microgravity. Yeah.

[00:28:20] [SPEAKER_01] Yeah, indeed. Well, you can read that story at space.com and maybe you're a glazier and you've got their window problems sorted out. Maybe you know something that NASA doesn't. Drop them a line, send them a bill. And good luck getting your money. No, I'm kidding. But yeah, space.com is the place to learn about windows in spacecraft. One little thing before we go, Fred.

[00:28:47] [SPEAKER_01] And this is a fascinating story in that it was an opportunistic photo that was taken. And, you know, right place, right time, exact right moment to create this little picture. I'll try and get Hugh to put it on our website as the cover photo for this week's episode, episode 669, just in case you're wondering. And see if you can take a look at it or you can look it up at the NASA website.

[00:29:17] [SPEAKER_01] But yeah, tell us about this photo, Fred.

[00:29:20] [SPEAKER_02] So it's one of NASA's astronomy pictures of the day, the APOD. And it's for the 22nd of September, 2026. So just a few days ago as we're recording now. And it's a photo by an astronomer from the Czech Republic who was aiming to get a nice silhouette of the International Space Station against the sun.

[00:29:49] [SPEAKER_02] And that's something that's been done before. There's a French astronomer who's kind of made an art of it. But this is somebody who's got a big enough telescope to give you a great view of the sun aiming to get the International Space Station silhouetted on the sun's disk. It's tiny compared with the disk of the sun, of course. And he indeed succeeded in doing that. But he also got a bonus because one of the exposures, and I'm sure he took several, the International Space Station does not dwell.

[00:30:19] [SPEAKER_02] It goes very quickly across the disk of the sun. Oh, yeah, it would. I think it's less than a second. But he managed to catch a plane as well going across the disk of the sun.

[00:30:28] [SPEAKER_01] Yeah, so what we're looking at in the foreground is the silhouette of a plane and behind it the sun. And in between or kind of hanging off the back of the plane is the International Space Station. And just to make it even more interesting, there's a few sunspots as well. It's a really great photo. Very, very... Yes, indeed, isn't it? Just a piece of luck, a chance opportunity that, yeah, turned out rather well.

[00:30:54] [SPEAKER_02] Indeed it did, yes. Very nice. And congratulations to Peter who did that. I think some of our listeners will probably be able to identify the aircraft. It looks to me like a military aircraft. Yeah, it does, doesn't it? Yeah. I wouldn't like to have a guess as to what it was, though. But yeah, well done. It's actually Petr, not Peter. P-E-T-R. He's from the Czech Republic.

[00:31:22] [SPEAKER_01] Lovely. Yes, go to the NASA website and just do a search for APOD 22nd of September 2026. If you want to have a look at it, you should be able to find it there. But I'll try and put it on our website as well as the cover shot for this episode. And that brings us to the end. Fred, thank you so much.

[00:31:41] [SPEAKER_02] Oh, it's a pleasure, Andrew. Have we got to the end already? Well, time goes fast when you're enjoying yourself.

[00:31:47] [SPEAKER_01] It does indeed. Yes. We'll catch you next time. Fred, thank you. Sounds good. Professor Fred Watson, astronomer at large. Visit our website in between episodes, of course, spacenutspodcast.com. And you can send us messages through the Ask Me Anything link at the top. It's marked AMA. You can visit the shop. You can sign up for the astronomy newsletter. Don't forget to leave reviews wherever you listen to us. Apparently, they help with something. Don't know. Don't know what.

[00:32:15] [SPEAKER_01] I guess it depends what kind of review you leave us. Yes. And thanks to Hugh in the studio. Couldn't be with us today. He was actually quite lucky. He took an opportunist photo. When I say lucky, yeah, the photo was a bonus. But the woman's husband was not thrilled and he's on the run. Anyway, he might be back next week if he's not in hospital. And from me, Andrew Dunn, thanks for your company. We'll catch you on the next episode of Space Nuts. Bye-bye.

[00:32:45] [SPEAKER_00] Space Nuts. You'll be listening to the Space Nuts podcast. Available at Apple Podcasts, Spotify, iHeartRadio or your favourite podcast player. You can also stream on demand at bytes.com. This has been another quality podcast production from bytes.com.