The Supermassive Podcast - Bonus Slingshots Christmas Presents Alien Communication

Episode Date: January 11, 2026

What would it be like to feel gravitational waves? How are satellites protected from extreme solar storms? How do gravity slingshots work? Are aliens potentially communicating outside of the electromagnetic spectrum? Plus Izzie, Dr Becky and Robert share their annual Christmas present recommendations.Keep sending your questions to [e-mail], Instagram @SupermassivePod or members can post on The Supermassive Club's forum. Join The Supermassive Club for ad-free listening, forum access, and extra content from the team. The Supermassive Podcast is a Boffin Media production. The producers are Izzie Clarke and Richard Hollingham.The Supermassive Podcast is a Boffin Media production. The producers are Izzie Clarke and Richard Hollingham. Hosted on Acast. See acast.com/privacy for more information.

Hello and welcome to another bonus episode of the Supermassive podcast from the Royal Astronomical Society. With me, science journalist Izzy Clark, astrophysicist Dr. Becky Smethurst and the Society's deputy director, Dr. Robert Massey. We do this every year. We're doing it again this year. Christmas is fast approaching. Christmas is coming and Becky's kicking back. I'm ready with all the little things that I want to make over the Christmas period. But we should also talk about all the amazing stuff that's out there that we can think of for the space lovers in all of our lives. Oh, are we on our own Christmas list? Yes.

And by that, I've been myself. I'm sorry. So, Robert, do you want to start on this one? What would you recommend? What's going on the Christmas list? I confess I cheated and asked people I knew in my local astronomy society for suggestions. It's shocking. But it did come out quite a shout out to.

I think that's a good idea. Yeah. Crowdsourcing. Crowdsourcing. Yeah, not cheating. That's using your initiative, Robert. Goldstar for you. That's more data.

So, no, shout out to Nicole, Jane, Karina, Taylor, Doug and Michelle for their suggestions. So they came up with things which I agree with, I think. A gift of a night at the local observatory. So if you're near somewhere like Hersman Sioux or Greenwich or these other places, that's a great Kielder, for example. That's a great shout, I think. An experiential thing where you say go along to an observatory. Because even if it's cloudy, you get the excitement of seeing a moderately big telescope.

and how it works and all the all the mechanics of that. It's usually a really, really great thing. Membership of a local astronomy society, no bias there, but I agree. A night sky guide for 2026, I've got one by, which is called, does what it says on the tin, stargazing 2026 by Nigel Henbester is a pretty good one. Binoculars, as you'd expect, always a good shout. And also, though, practically, I also agree with this. Maybe they should be star-themed or star decorated, a thermos flask hat, scarf, and a folding chair

for doing things like watching meteors. Like knit someone a little like stargazing blanket or something or like quilt a blanket or Just borrow the centenary quilt. I have no knitting skills but I think it's a great idea. Little hand warmers and things like that. That's the other one. It's a little stocking fillers, you know. A little stargazers kit to getting through like a cold winter's night.

Exactly. And then the other things they said were things like if you know people and you can do the research, things like nice eye pieces for people already have telescopes. Astronomy themes stationery. which goes in with that. And then finally, the European Southern Observatory has a gift shop, which I didn't realize. So there are things there too. So, yeah, have a look around those.

I think that's got to be enough to get people going. Oh, my gosh, definitely. It also makes me think, like, why haven't we done merch? I want my own supermassive thermos frasque, please. I know. I'm suddenly thinking that we need to be wearing supermassive baseball caps and jackets. Yeah. Well, get knitting, is he?

Sorry, guys, got to go. I can't do the podcast anymore. What about you, is? What would you like for your? space-themed Christmas. Well, we have to talk about Project Hell Mary again. I knew you were going to nick mine. Sorry, but it was a great recommendation from you.

I've now since read it or listened to it. You're as obsessed as I am. It's amazing. I tell everyone about it. So I just think that is, I love getting books at Christmas. So I think that's just such a good presidency of someone. Amaze. Yeah, Amaze.

There's BBC Earth actually have a really good merch store in terms of T-shirts. I love a print T-shirt. So they've got some of the nice guy. A really nice satin one. Yes. I love. It's like, it's very cool. And there's one of like the moon and all of the craters and like in just really artistic detail that I love.

And they're quite, they're from a sustainable company as well, which is a little extra. Same as my much. There we go. Becky's smaller. Same company. Sustainable merch. Made on the aisle of white in the UK. Lovely.

And actually my final recommendation is something that a friend got me, but they are so. handy and it's a collection of space postcards so they're all images from like Hubble, lots of other telescopes, a mixture of NASA and ESA missions as well. And so whenever you want to write someone like a little thank you know or anything like that, I just send them a space postcard and I love them. So I think that's just probably one of my favorite things I've had. I'm now wondering if you can get space stamps to go with your space postcards and whether that would be a good gift for a stamp collector who is also an astronomy. There must be. There must be. How about you, Becky? What are you thinking? Well, I figured you guys covered the stocking fillers and the smaller presents. And I thought,

well, I'll go big. You're going big. Okay. Well, I figured like, you know, time is the biggest gift you can give anyone. So obviously, planning any sort of trip where you're like, we're just going to go camping this weekend in this dark sky site near us. It's all booked in, whatever. You know, give that gift of time with someone that you love. Do that. That would be a great gift, I think. Strong agree. And you want to go really big. There is an eclipse coming up in 2026, the 12th of August.

It goes across Western Iceland and northern Spain. So your astronomy friend out there is thinking about this already, right? If they weren't, they are now. And they're probably thinking, how can I see this for myself? How can I see a total solar eclipse? And so, you know, you could help them out. You could get them an airplane gift card or, you know, a holiday company gift card, like an Airbnb or a Verbo. Other companies do exist.

You know, things like that that could help towards planning the trip for the total solar eclipse of 2026. Amazing. Yes, please. Sign me up. I hope my family are listening to this. I'll be like, So, Bill Bow, that seems nice. I keep thinking about this and I keep thinking, do I go northern Spain or you can technically, you should technically be able to see the total solar eclipse in Recovic in Iceland. and it's at sunset and I think seeing a total solar eclipse at sunset would be absolutely incredible however Iceland you're not known

for reliable weather there's that whole saying in Iceland like if you don't like the weather wait five minutes and it will change and I'm like I but will it it doesn't scream stable does it

because I don't really want to watch a total solar eclipse in five minute intervals of getting pelted by hail and then be like, oh, what a pretty sunset. Eclipse. Hale. Or just the five minutes happens to coincide with the time of the eclipse. Yeah. That would be my worry. That would be the...

You need to go to Iceland and hire a plane to be above the clouds or something. Yeah, okay. That's the ultimate luxury gift, isn't it? Probably. You see the northern lights at the same time, maybe. That's what people wonder about. Wow. Yeah.

All right. I'll get on the phone to my friend with a private jet. No. I don't have one of those. Okay, well we've got time to plan. We've still got time to plan. So, right, I think we should probably get onto some questions as well. So we've had a few posted on the Supermassive Club. There's a link in our bio if you'd like to become a member too.

Not only does this support the show, but you'd get ad-free listening. And we'll also be doing a special Q&A for our members next month too. So Becky, let's start with this one from David Laar, who asks, what would it be like to experience gravity waves that could be felt? Would it feel like a stretch or a pool, like a building or ship undergoing something like an earthquake? I understand you would have to be relatively close to the source of the gravity waves, but I also strongly suspect there's some distance at which you get, i.e. 1% strain of amplitude of gravity waves.

And what would that be like? Wow, a 1% strain is insane. That's all far beyond what LIGO can detect when we think about gravitational waves that we detect on Earth. For context, like the strain, what we call it, the gravitational wave that a lagger would detect would be like 10 to the minus 21, 0.20 zeros and then a 1. So when we talk about that, what we mean by strain is like how much the length of a meter would change as the gravitational wave passed by.

So like 10 to the minus 21 per meter, it would change. So a 1% strain would mean that a meter distance would change by a centimeter as the gravitational weight passed through, which doesn't sound like a lot. but if you were to feel that. So, I mean, you literally don't feel anything when a gravitational wave passes through in terms of like the ones that Ligo detects from merging of two black holes.

You feel nothing. But if you were to feel a one centimeter in every meter change in every direction, so you know, across your shoulders from your head to your feet and, you know, from your nose to the back of your head. Yeah. Like, you love. In my mind it's like, you know, like a body roll, like Mexican wave kind of like.

Yeah, it's, I imagine it wouldn't. I mean, you referenced an earthquake there, David. I think it would be very different to an earthquake. An earthquake is something where the thing around you is moving, but you are not. I imagine what it would feel like is being sort of like the universe is stress ball. Yeah. You know, you're just getting squashed and what's the opposite of squashed? Oh my God.

But stretch. Stretch. Thank you. It's not stretched though, is it? It's expanded, isn't it? It's like it would feel like getting just sort of squashed and expanded, you know, as the wave oscillates through you. I feel a little bit nauseous. That's a little bit like a human accordion is basically the motion that you just created.

So I don't think it would feel particularly nice. To actually get a 1% strain, as you. you suggested, you would have to be a lot closer, yes, to a black hole merger or a pulsar or whatever it would be that you wanted to get close to. But we're talking like instead of the light years, millions of light years that we are away from the things that we detect now, we're talking more like a few kilometres away. And then I think gravitational waves are the least of your worries if you're getting to kilometers away from a black hole merger. Okay. Well, that's unraveled quite a lot. Thank you, Becky.

But Brian Rosks asks, if we got another Carrington-level event, how long would satellites and such need to be shut down or protected? And when they do, are their orbits affected? And is there a chance they lose too much momentum? Thanks so much for what y'all do. He said, car pay space. Sorry, you want to say y'all again then? No, Becky. I was trying to just get past it. Thank you. How would we pronounce this? Carpe, Spatium, Cayley?

I think it's fine because it's Latin, so it can be pronounced any way that you like because nobody speaks Latin. So it means seize the sky, so thank you, Brian. And I will revise some Latin for you. But what do you reckon, Robert? Well, this is a good cheery question there, Brian. So just a reminder, we obviously covered this not long ago,

but a Carrington event is the one like the big solar flare and following coronal mass ejection back in 1859 that was incredibly dramatic explosion on the surface of the sun, then this big cloud of charged particles slamming into the magnetic field of the earth and leading to early electrical systems like telegraphs burning out or being possible to use them without batteries. And today that could be a lot worse because we'd see damage to power grids and satellites potentially effectively destroyed, no longer able to operate. So anyway, the short answer is that it's really, hard to fully protect them if we have a Carrington level event. And it happens to have investigated back in October by the European Space Agency. So the first warning you get is a big surge in x-rays and ultraviolet radiation coming at the speed of light. And that's observing the solar flare. And even that might be enough to disrupt radar and navigation systems. And then there's a wave of high energy particles that are traveling at high speed that disrupt electronics a bit. And all that is a warning of something that might come along as early as 10 hours later, it might be a few days later, and that's what brings you your bigger problems.

So you could see overloaded power grids on the ground, induced currents, destroying them in some parts of the Earth because it's very hard to protect them. Badly damaged satellite electronics and the Earth's atmosphere expands somewhat or can expand somewhat and then get more satellites reentering and probably more likelihood of in orbit collisions too. So all this is not great. And decay of orbits too, right? Exactly.

It's exactly. It's really not great. All of a sudden you could have satellites that were like, well, that was in a nice stable orbit, but now it's going to spiral to the ground. Exactly right. And it's really, really difficult to completely protect satellites. The study concluded that there wasn't really anything you could do. It would have to be more about resilience and then thinking about how you recover and making sure your systems on the ground are able to pick things up quickly. Obviously, particularly in areas like power balls. So areas like timing because we rely on very precise clocks for banking transactions and all those kind of things. So those things might grind to a whole. So it's really trying to recover from that seem to be the key message. You can protect your satellites a bit, but you shouldn't assume that they're fully resilient. It's just a really tough thing to deal with. The good news, obviously, we think, is that these things are quite rare.

So the Carrington event more than 150 years ago, 160 years ago. Other events like it, we see from evidence, historical evidence, descriptions, evidence in the impact in things like tree rigs and so on, believe. And so we know that they don't happen that often, but it's still something to be prepared for. So I can't give you better news like how long they're on. offline or anything like that. I think it would be some satellites are damaged or no longer working. Maybe some will survive.

We're going to have to launch more to make up the gap and accept the fact. A lot of them are going to reenter the Earth's atmosphere collide and work out ways to deal with all that stuff. One thing that literally just occurred to me, as you were speaking, was when did the Carrington event happen in the solar cycle? Like, was it just before the peak? Was it at the peak? Was it just after? Because I was about to say, oh, well, we're literally just past the peak and we're starting in 2026 to sort of, drop off again into the solar

work our way to a solar minimum. So I was like, are we safe? And I was like, but I don't know. Can I say that? Like, when did the Carrington event happen in terms of activity? I don't think we are safe. I think the... Yeah, we're never safe, but you know what I mean? Like, I'm like, probability speaking, probabilistically speaking, are we more safe, you know?

Yeah, I think the answer is that even at solar minimum, you still can get events like this. They may be less common, but they're still there. And I remember reading a paper or a coherent conference presentation saying that there's still as much instability and so you shouldn't assume total safety. It is true, I suppose, that when you've got many more sunspots, you're going to get many more bigger sunspots. And so the associated events are more like it happened. But I don't think we're completely safe at all. And it's a good question as to whether how it compares to the sunspot cycle, we'd have to look up the historical records of that to check, I guess.

It was one of the biggest sunspots ever observed. We will report back. Hang on, producer Richard has entered the chat. He's our minion who Googles things in the background for us. Yeah, so I had a quick Google. And according to a couple of sources on here, including space.com, the Carrington event happened. September?

September? Yeah, so that was, what, 1859. And the solar maximum was in 1860. Wow. Six months before. Yeah, so just before. So I guess, you know, towards the solar maximum. And no one say anything that you're thinking

because we have a history of jinxing things on this podcast. So we are just going to move on to the next question. I'm literally about to say something. I will not say it. Okay, so Becky, listener, Mark Friend in Virginia, has a question about gravity slingshots. He says, Hello, Supermassive Team.

In your episode about gravity, Dr. Becky explained how we use gravity of planets to accelerate space probes with a slingshot manoeuvre. As I understood her explanation, the probe steals energy from the planet as it accelerates towards the planet and keeps that energy in the form of increased speed as it passes by. What I don't understand is why the planet doesn't reclaim that energy as the probe passes by because Newtonian law tells us that for every action there is an opposite and equal reaction. Please make my head stop hurting over this conundrum.

much and thank you for your podcast. Okay, Mark, I originally thought this question was very simple because I was like, you said it. Every action has an equal opposite reaction, which has to be said in the Hamilton rhythm, as always now. The planet is the thing that loses energy as the spacecraft gains it. But then I actually realize what you're asking here is the fact that, okay, the spacecraft is getting closer to the planets and it's gaining energy.

And you're saying, so as it loops around the planet, why doesn't it then lose energy again as it loops around the other side? And I realized your issue here, your conundrum, your paradox, if you will, that you create it in your mind is you're forgetting about the sun. This is not a two-body problem between planet and spacecraft. It is a three-body problem. So yes, as you're thinking about it, in the frame of reference of the planet, you're thinking about it as if the planet is stationary. And it's just the spacecraft that's looping through it. But it's not, right?

The planet is in orbit around the sun, as is the spacecraft as well. which is also in orbit around the sun. The planet is moving. And so in the sun's reference frame, what's actually happening is the planet is giving the spacecraft a boost on its orbit around the sun. And that is the issue there. It will lose a little bit of energy climbing out of the planet's gravitational well. But overall, what happens is the spacecraft does get a boost in its momentum from the planet.

it. Ah, so you need to look at it as the biggest system. That makes sense. Okay. I hope that helped, Mark. And I have also now learned something as well. Thank you. You've learned about three body problems and reference frames.

Although it's not just like learn also. It's like something that we all need a reminder of all the time is that like how you're picturing it in your head is like you've forgotten about like a key thing. And it's always come back to reference frames. Like anybody who's ever studied physics ever is always like, oh, the reference. frame. Like, why does it matter which reference frame I'm in? It always matters. It always matters. Okay. Thank you. And Robert, here's one from Olli McCabe on email. I love this email. He says, Gooday, oh no, we're entering Gooday into the Hall of Fame with Y'all. Okay, anyway.

Well, just have a collection of you doing all of these, like, other accents. Followed by lots of very British apologies. Like, I am so sorry. Sorry. Sorry. Sorry. Goodalee, lots of love from Toronto, Australia. Anytime I sit down to write my sci-fi story, I always end up with this question, and then it's all I can think about. So the whole thing with the Fermi paradox is, if life could be everywhere, why isn't it, or why can't we find it?

And if at least one alien civilization was similar to us, it would be spitting radio waves and such out of the wazoo with no regard for us and who could listen. But we don't get any radio waves that, aren't our own. My question is, is it possible that aliens are out there and instead using something other than the light spectrum to communicate and that we as humans are the exception? The only thing I know of of that kind that works like light is gravity to an extent because it goes at the same speed, but surely that would have some sort of implications because gravity

also holds everything together and we also have LIGO that hasn't detected anything like that. Over to you on that one, Robert. Thanks for that. Well, Ollie, another great question. I quite like thinking about this stuff. And a reminder, the Fermi paradox is the, well, if there are aliens, why aren't they here? And it's a starting point is that it's a hint that we're effectively alone in the cosmos and perhaps either the only advanced species to have existed or at least the only one around now.

The likelihood seems to me that electromagnetic radiation, so including light, is going to be the default way to communicate. And simply because we can transmit it most easily and radio and maybe, maybe light in some situations of the parts of the spectrum that are best suited to messaging. And that's partly about the amount of information they can carry to. You can generate strong signals, carry lots of data and therefore it's a good communications medium. And then there's a lot of debate about what kind of signals will be sent and how we'd recognize that they are a signal at all, how we'd translate them, whether and how we should

respond, knowing perhaps that it might be hundreds or even tens of thousands of years before we get our reply. So all these ethical debates around that. And we could, I suppose, as an alternative to do things like send a beamer particles at light speed, but it's not easy to see how they'd carry enough information or near light speed. And as for gravitational waves, or this follows on from Becker's earlier answer, if they're significant enough that you can easily detect them. And bearing in mind, they're incredibly hard to detect right now. And you're talking about shifts in LIGO of a small fraction of the size of an atom when a big gravitational wave event comes through, it's really hard to see how we're going to find details in those signals or

recognize them in their artificial, let alone how people would generate them. Because bear in mind that the neutron stars colliding billions of light years away, these are incredibly powerful events. And it's very hard to imagine any civilization that there'd be godlike, right, to manipulate the universe to that extent. It's very hard to see how we could make those in a benign way. even if you're able to do so, that they didn't then destroy the species doing it. So beyond that, look, it just seems incredibly speculative. Fascinating, but speculative. I mean, are we talking sort of signals through wormholes

or some kind of hyperspace, all these science fiction tropes? We're not even close to being able to do these things. So I think that my honest answer, Ollie, is it's best left to science fiction writers like you to inspire us and encourage people to think about it more. And, you know, I admire you for your amazing imaginations and envy them to some extent, too. So great question, but I think my hunch is it's going to be electromagnetic radiation as the default messenger in the universe. Yeah, amazing question there from OLLI. Thanks, Robert. And keep the questions coming.

It's at SupermassivePod on email. No, it's not. It's at Supermassive pod on Instagram. Supermassive Pat. I'm Australian now. Keep the questions coming. It's at Supermassive pod on Instagram or you can email your questions to at. Oh my God.

We cannot. We can never do a 9 a.m. recording ever again because my brain is not here. Where do you think my brain is? Yes. Fair enough. Keep the questions coming. It's at Supermassive pod on Instagram or you can email your questions to podcast at rass.ac.com. Or join the Supermassive Club and we'll try and cover them in a future episode. And we do have our January Q&A coming up. So get those questions in, please. Oh yeah. I do like this tradition of a January. Q and A. It's like, hello listeners, please piece together our show for us because we...

And also, it's just like... Everyone's had some time off over the holidays and just sends us some absolutely bonkers questions that we start the year going like, okay, let's dust off the cobwebs of our minds. Off we go. That's true. We get like that I had three glasses of port over Christmas and this came to me and also I couldn't sleep over Christmas so therefore I came up with this question and like, wow, these are incredible. But before we get to that episode, we'll actually be back in a few weeks' time to close out the year with an episode about time travel, which we have been promising you all for a very long time. But until then, everybody, happy stargazing.