The Supermassive Podcast - Protecting Our Dark Skies

Episode Date: December 1, 2025

What are the threats to our dark night skies? And what needs to be done to protect them? Izzie, Dr Becky and Robert explore this important topic and head outside (...and the weather was not on their side!) Thank you to Dr Samantha Lawler at the University of Regina in Saskatchewan and Andy Lawrence, the Regis professor of astronomy at the University of Edinburgh. Don't forget to 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. Hosted on Acast. See acast.com/privacy for more information.

When I go outside at night, I can easily see the Milky Way. Well, you can't stop light pollution completely. What's the darkest and best night sky that you've seen anywhere in the world? Hello and welcome to the supermassive podcast from the Royal Astronomical Society. With me, science journalist Izzy Clark and astrophysicist Dr. Becky Smethurst. This month, we're exploring dark skies. What are the threats to our Dark Nights skies? Why is that important?

And what desperately needs to be done to protect them? I mean, how do you feel about this topic, Becky? How much do you think about Dark Skies? I don't think you're ready for what me and Robert will a leash on you. I go to be like, and let's dial back the rants, everyone. And obviously, Dr. Robert Massey is here too, the deputy director of the Royal Astronomical Society. You're already laughing away, Robert, as well.

I feel like we're going to unleash. I definitely am. So I know we usually ask you a question to kick off the show, but I thought we should take things outside. Hang on, where are you? I can't actually see you. Wait, give us the wave. Let me go.

This is absolutely mad. This is like sideways rain. As it is, I have to say, this is one of the craziest things I've done on the Saturday night. But look, isn't it great? It's completely dark. Here we are on a beach, in a storm, listening to the sea and the wind, and it's dark. That's all I can say. Right, so I'm going to set the scene. We've come down to the South Coast.

We are standing on a beach in a storm, basically. You might already hear that on the audio. where exactly are we Robert? So we're at Berlin Gap which is part of the Seven Sisters and part of the South Downs National Park and the whole of the South Downs National Park stretching across Sussex

is supposed to be a dark sky area so it's supposed to be protected here we are in the dark more or less completely dark we can see just about the lights of Brighton over there to the west and if we look to the east East-Born is actually just around

the headland over that way but we really can't see very much at all Now for me this says look it's crazy right this is a tempestuous night and we've got the elemental forces the sea and the wind and all the rest of it but what I really notice well is just how dark it is now we turned off the light a minute ago and already I can see I can see a bit more you know I can see the clouds above but they're not actually that bright you know they're pretty dark clouds above us that's a really good sign because you know if you live in a town or a city you're so used to this the clouds being lit from underneath. So I think, you know, I really want to come back here on a properly clear night, which is obviously what we'd have liked tonight. But you can see just how great a dark place is. It's actually amazing.

So we walk down here with a lamp. We've just turned it off and I can't quite believe how dark it's got. I know that sounds stupid. We're in a dark sky area, but it's quite something. So why are dark sky areas like this so important? You know, I think most of us, The majority of the population lives in a place where we used to streetlights, we used to ambient lighting, from advertising, from our neighbours, from cars and all these

things. I think it's really great to be able to step outside of that, just go a relatively short distance. We haven't come that far tonight. I live in Lewis. It's not a long way away. It's important to be able to make that connection to come somewhere where it's genuinely dark. Now, obviously, obviously it would be even better if we were doing this under a panoply of stars, but it does say, look, you can step away from that. that intense urban environment you can look out at how how kind of nature is supposed to be we don't want all lights to be switched off that's very much a thing about tackling light pollution is not making everything completely dark but i do think we need those dark places too just to remind

us and to just actually i think also take away the fear you know i actually come down here okay i'm not here on my own right you know we're here and all the rest of it but it doesn't feel fearful. It actually feels really quite special and a bit crazy because it's a storm but it feels great you know we're here it's dark isn't it wonderful you know I think I think that's something to celebrate it definitely feels like we're out on an adventure that's for sure so how many dark sky areas are there in the UK you know where else can people experience this level of darkness ideally not in the middle of a storm but uh you know there are now a lot of dark sky places of different sorts in the UK and they have different

designations like reserves and parks and so on you can find maps of them online they tend to be in places that are sort of national parks or otherwise wildlife protected areas I think we probably have to have more of those nearer to our towns and cities as well we shouldn't just say it has to be

somewhere really remote you know I'd like them to be near enough that a lot of people can access them the south towns isn't bad for that because quite a lot of people live near here so there are you know you've come down from London as you've done this evening and that kind of thing to get to it but yeah you can look online and find them but you can also one other thing I'll mention is that we're getting going again I'm involved with this project to get these dark sky discovery places up and running again and to relaunch this project there are quite a lot of those

designated around the UK they're not necessarily all that dark all them but some of them really are and the thing about those is that they're also designed to be accessible so you can get to them you know you can get to them 24 hours a day without having to worry you know there's parking and there's access and it's safe and all those kind of things. So have a look, but there are more and more of these places being designated. I just think it needs to be almost the norm rather than the exception, that there should be lots more places like this. Yeah, and it's really nice to know that somewhere like this is accessible 24 hours a day.

So obviously we've not chosen the ideal night to go stargazing because we are absolutely covered with clouds and the sea is roaring behind us. But let's talk about darkness. how that is measured. So how is there a measurement for a dark sky and how dark it can actually get? Yeah, there's this thing of the Bortle scale which is basically I think from one to nine, nine being very light polluted and one being a perfect sight in the middle of an ocean. So in other words, as far away as you can possibly get from any artificial lighting, you're really looking at the sky brightness and that's going to tell you about the faintness

of the stars you'll see with your eye and also obviously how much you get to see with a telescope as well. Right. I think it's probably time that we head back up and maybe go to a pub. I think a pub is cooling. I think that's entirely legitimate. I mean, you know, everybody else is doing something like that tonight and we're on a beach in the pouring rain. It's fantastic. Oh, it's so nice to be outside. Now you're a bit cold now, you guys. It's just like, it's just warming up now. So, Becky, where are some of your favorite night skies in the UK? Oh, I have a question I love

like Northumberland and Exmoor some of the sort of official dark night skies that I visited and they're just incredible like there's just nothing else compares to it like I'm going to bring a dark night sky you know tonight from my back garden and then you go there and you're like no I absolutely don't

you know it's just amazing I remember staying in a place just on the sort of like edge of Exmoor and it had like a skylight window right above the bed Oh, amazing. And we just left the blind open and I woke up in the middle of the night

and it was just like, it clearly opened my eyes and was like, oh my gosh. There's just so many stars. But, you know, it's not just the official dark sky sites. You know, I've seen some cracking night skies from the places like the late district, the peak district, along the South Coast path as well in like Cornwall, Devon, Pembrokeshire,

like just some incredible night skies. Anyway, you can get away from, you know, the light pollution of cities is just going to be amazing in comparison. Totally. I totally agree with you as well on Exmoor. I've been staying in this little town called X-Word with my family since I was teenagers. We used to go camping there. And it's one of my favourite things.

Every time we go there, I'm just like, I can't wait for it to get dark. Like, let's go. Because I just want to see the sky. But we are seeing growing threats to our dark skies. So let's talk through those. What are they? Yeah. I mean, as I mentioned, light pollution from city street lighting, right, is the big one.

You know, there's lots of scattered light in our atmosphere, which makes the sky brighter and blairs out in, you know, most stars. So you can only really see the brightest things from cities these days. It just adds this big sky glow, you know, if you've been driving at night, right, you know where the nearest city is, right? Because you look one direction and it's dark and you look in the direction, there's just this just like ambient glow everywhere, yeah. And you can really see that when it's cloudy actually. Obviously, you can't see any stars when it's cloudy, but it really demonstrates how bad the issue is because the clouds reflect that light back down again

and you can really, really see that ambient glow. Obviously, in terms of threats, you can add to that sort of increased atmospheric pollution as well because, you know, from urban areas, if you've got dust, aerosols, any sort of heavy molecules, like particulates that come from, you know, vehicles, exhaust, things like that, they're also going to scatter light. And so that makes the sky glow even worse.

worse, it really increases it. You could add increased air traffic to that list of threats to the night sky as well. I'm not talking about obviously like the lights from air traffic isn't really going to be a big issue, but, you know, increased contrails is just water vapor, more water vapor in the atmosphere also scatters more light. And, you know, if you have a contrail across the sky, that can reflect light back down as well on a clear night. And so that also contributes to sort of like washing out faint stars.

Then, of course, you've got the thing. everyone is very worried about that and that is satellite mega constellations which have been increasing threat over the past five to 10 years like 10 years ago I don't feel like anyone was having these conversations whereas now it's all we can talk about

the likes of Starlink one web, Amazon, Leo, etc., right? They've launched a combined total of around about 8,000 satellites so far but with plans to launch I've seen numbers that range from like 50,000 to 100,000 right, in the next decade. Just to put that into perspective,

there's like 12,000 or so active satellites at the minute in orbit so it's a huge huge increase and obviously the reason that these companies want to do that is to provide internet anywhere on the globe right which is great I think most people sat here of relying on the internet listening to this podcast I've streamed it over the internet being one of those reasons but there is a massive issue for night skies because satellites do reflect the light of the sun back to us so that we can see them on earth they look like slow moving dots in the sky right if you've ever been in a dark sky site you will probably have seen a satellite.

They're very, very common. But with these constellations satellites, they're often grouped together, especially after they've just been launched. So you see them in a line? You must have seen it, Izzy, before. Yeah. And I was going to say,

I think I've told this story before, but there was a time where I was in Marrakesh, and they'd just launched one of the Starlink mega constellations, and you could just see, like, these perfectly spaced little dots going through the sky. In a trail, yeah. Yeah, in a trail, and they're all linked together. It was interesting to see.

see, but at the idea of having however many of those in the night sky, you can quickly see how a little tricky things can get. Yeah, and suppose that, you know, they do separate over time after they've been launched. It's only straight after launch that they're clustered together like that. But I think when you think about it from a public perspective, there is that risk of, you know, being somewhere so remote that you do feel like you're completely cut off from the rest of the world, you know, and you can enjoy this beautiful, you know, night sky within nature and things like that and then all of a sudden it's like, oh, no, you are still connected because there's

massive amounts of satellites going ahead. There's going to be nowhere that's truly isolated anymore on earth and no one that will have, you know, these pristine night skies. So that's obviously a threat, but the big issue for me, especially as a professional astrophysist to rely on ground-based observatories to do their research, there is a big threat to professional astronomy as well, not just like visible light astronomy that we do, you know, the kind of light that we see their eyes, but also to radio astronomy because all these satellites communicate with radial light, long wavelengths of light that can interfere with what we can then detect coming from black holes and stars out there in the universe and things like this. So ESOs, the European

Southern Observatories, report on the impact of satellite constellations that they did is very informative on this, that they did a simulation of what it would entail if there were like 100,000 satellites launched within the next decade or so. And what they found that it would mean that any given one time there would be 5,000 satellites over the horizon. Now, most of those are concentrated at low altitudes. So if you think about when you look

at the sky and you look towards the horizon, there is sort of more of a bit of a general glow and scattering just because you're looking through more atmosphere. So a lot of them are not that big of an issue in terms of the fact they're going to be concentrated at low altitudes. We can deal with those. But the simulation still found

that if you did launch 100,000 satellites and took an exposure with a telescope that was pointing directly upwards just for 30 seconds, which is a very short exposure for a professional astronomy. Like my exposure is an hours long, right? But for 30 seconds, you would have on average one satellite crossing that exposure. And the issue here is not necessarily the number. Like if you have a satellite crossing the exposure and as long as it doesn't cross exactly the thing that you're looking at, you can maybe remove it.

But the issue is the brightness. because if that satellite is so bright that it completely saturates your incredibly sensitive detector, then you've lost your entire observation, minutes, hours, whatever, gone. You know, it's just a waste of time, essentially. And so there is a real fear in the community that these megac constellations could wipe out any and all ground-based astronomy that we do because there's just no regulation. There's no international rules for these megac constellations, like companies have to follow to be like you must adhere to these regulations in order to

protect this at the moment. Yeah, and it is a growing concern and it's something that our next guest, Samantha Lawler, is also really worried about. She's a professor of astronomy at the University of Regina in Saskatchewan in central Canada and I caught up with her recently to talk about the number of satellites that are being launched and what effect they might have on her view of the night sky. I can easily see the Milky Way. I can easily see the Milky Way. I can can see auroras, because I'm far enough north for that. I can see satellites, of course. There's this this Bordle scale. Bordle 9, I think, is the worst. That's no stars, bright city lights. And then Bordle 1 is like perfectly dark skies, no light pollution at all, right? So where I live,

I'm still well within the light pollution from the city, but I'm about a four here at my house. But, like, any time there's any kind of astronomical event, I'm so lucky I can go out, like, Comet Lemon. Comet Lemon was gorgeous from my house. And I can drive for an hour and get to Bortle 2. It's amazing. It's amazing. I am so grateful that I get this. And I am so deeply jealous.

I'm on the outskirts of London. So, you know. And you just mentioned satellites. So when did you first become annoyed by satellites instead of being happy when spotting one? sometimes if I'm introducing someone to stargazing, that I will point out satellites because I think people are surprised when you see them. So how has that attitude changed for you over time? Yeah. So I moved to this farm in 2019 and that's also when Starlink started launching. I can see the Milky Way from my house for the first time in my life. And now there's all these

satellites. How bad is this going to get? So that was definitely when the transition happened for me. But part of that was just having access to dark skies. And so with satellites and where I live happens to be a little bit higher than 50 degrees latitude, right? So what is London like 50 or something? So that's like the densest band of satellites is right over us just because of the orbits that Starlink has chosen. So the light pollution from satellites is not even evenly distributed around the world. It's different depending on your latitude and depending on the time of year. And I wrote a paper, a research paper, with a couple of other astronomers trying to predict when we have 65,000 satellites, how bad is this going to be?

And it's been horrible to watch that prediction come true. Can you just tell me about what you study and then how satellites, different kind of pollution and noise, impacts your data? I am just wrapping up a survey on the Canada-France-Hawaii telescope looking for new distant Khyber Belt objects. and the way that we discover them is wide field imaging. So we point the telescope at a spot on the sky, long time exposure. We're doing like three hours of five-minute exposures. And during that time, many satellites fly through the field of view.

And wherever those satellites fly through, we've lost that data. It's like effectively making our telescope smaller and smaller. And right now we're still able to do most of the science that we set out to do. but it's definitely getting harder and harder. This is a huge problem for the Verra Rubin Observatory, and it's also a huge problem for radio astronomy, right? So radio telescopes are built in these very remote locations, far away from cities where there's not a lot of cell towers

or radio transmissions happening. And now all of a sudden, especially with new direct-to-cell satellites, it's like the cell towers are flying directly overhead, blasting incredibly strong radio signals right into these very sensitive telescopes. So I've spoken to many radio astronomers talking about just how much harder their jobs are getting, right? There's entire swaths of frequency that they just can't study anymore. And just to really spell this out then, so you're saying like visually, you've got satellites going across any observational data that you're taking,

but then even if you're looking at the frequencies of it, then you've got the frequencies that all of these satellites are operating at as well. Like it's all in lots of different directions, a headache. Yeah, yeah, exactly. And a big part of this is just how many satellites there are, right? There's been satellites broadcasting from orbit for many years, but the sheer numbers have just skyrocketed in the last few years. Yeah, and I want to talk about that actually, because you've made a projection of how many satellites will impact astronomical observations in the future. So can you talk me through that? What did you find? Yeah. So for our paper a few years ago, we said 65,000 satellites, and that is how many satellites

Starlink, One Web, Amazon Kuiper, and one of the Chinese megaconsolations have asked for. And I say megaconsolation, so these are constellations of satellites working together that are very disposable, right? They put these satellites up, and they only have very short lifetimes, and then they burn them up and send up more, like they're disposable, even though they're large. They're like the size of big trucks, so they're not small satellites. But yeah, so we did 65,000, which I thought was a ridiculous number at the time. Come on, we're not going to get to 65,000 satellites.

But here we are at... In what timeline? That was supposed to be within, I don't know, 10 years or so. But we're going that direction, right? There's almost 9,000 star links in orbit today. There's close to 14,000 satellites total. and other megac constellations are starting to launch. We could get to very high numbers.

Yeah. And do you think there is a balance that can be struck? Because obviously, we do need satellites like communication or weather monitoring or anything like that. What do you think that balance is? Can there be a balance? I think we have to accept that there are hard limits to how many satellites we can have in orbit safely, right?

Right now, for example, Starlink reported in November 24 through May 20, 2025, they do a collision avoidance maneuver every two minutes on average. Their orbit is so dense that they are almost crashing into each other every two minutes. That's wild to me. That can't be sustainable. And they keep adding more satellites to those orbits and burning them up in the atmosphere. Like satellites have a very different composition than naturally occurring meteors. Meteors are rocks. Satellites are metal and plastic. And that's all just being added to our upper atmosphere. Starlink is burning up one to two satellites per day right now. At their peak operation, they could be burning up one per hour on average. Like, it's wild. And some of these pieces are hitting the ground, right? The throwaway mentality and the high numbers, that is the problem, right?

Like, satellites are incredibly useful. And the engineering challenge now is how do we deliver those services from orbit with fewer satellites, that have longer operational lifetimes. That's what we need. But I'm afraid that without that strong regulation, it's going to take a terrible disaster in orbit or going into Kessler syndrome, which is this worst case scenario,

then nobody gets to use orbit. And I really don't want to get there before we realize that we need this strong regulation. But that was really depressing, and I want to end on a positive. One thing that I always tell people, especially, yeah, professional and amateur astronomers, like showing people the night sky is so important,

and I know so many of you volunteer your time to get your telescopes out and show people beautiful things in the sky, please keep doing that because that's so important to show people what's changing, what we're losing, what we need to fight for. So please keep doing that. Thank you. Thank you to Samantha Lawler from the University of Regina.

So Becky, Samantha spoke about Saturday, light's there, but also mentioned light pollution. I know we've touched on this a little bit more. But when we talk about light pollution, what exactly do we mean? And why is that a growing issue? Yeah, I mean, we mean extra light at night that shouldn't be there. And this is not just a concern for astronomy either, but also like an environmental concern in terms of what effect it has on birds and any sort of migratory species, but also any animals at all that could be affected by extra light being there. And I think a lot of people in the, let's call it the 20th century generation, rather than I want to call anybody old,

would report remembering like much darker skies when they were younger compared to now. And that is due to just a trend of the growing number of streetlights in urban areas, but also the type of street lights as well. So there was a recent study that was led by the University of Exeter that showed that light pollution, visible at least to satellites in orbit. I know we're talking about impacts of satellites, but satellites are useful in this case. You know, visible to at least satellites in orbit

has increased by at least 49% over 25 years, and that's a global figure. It's more in some areas and obviously less than others. But that's only the light that's detectable to satellites. On the ground, it's likely to be much higher than that. It's actually like it that light pollution has tripled, is some estimates that you see. And the reason for that is the switch from yellow,

sodium street lights. Do you remember when you were yonder, right? Yeah, the lovely little old glow. Yeah, that very, very distinctive yellow colour comes from the fact that basically there was a bit of sodium that was giving off a very specific wavelength of light that is very unique to sodium. And in

recent years, there has been a switch to the much cheaper and more energy efficient, hooray for energy efficiency, LED bulbs. But the problem with LED bulbs is that they emit light at all wavelengths, not just the very yellow, yellow wavelengths of sodium lights, and particularly at blue wavelengths, which are much shorter and scatter

more in our atmosphere. That's why the sky is blue during the day, right? But it also, what it means if you have a lot of blue light at night, you're just going to get a brighter sky at night as well with more sky glow. Combine that with the expansion of cities and the increase in air pollution, also causing more scattering, more air glow. You've just got a recipe for the loss of our night skies in any urban areas. Now, direction. lighting does help somewhat. This idea of instead of having just a bulb that's radiating in all directions, you sort of cap it. Have a little hat on it. A little hat on it. Yeah, point it down. Exactly. Yeah. So it stops it pointing upwards. It puts the light where we need

it down on the streets. It doesn't help enough though is the problem, especially it doesn't help at least to combat the uptake and the use of LEDs because it's not just the switch and street lamps, but also because LEDs are cheaper. People are like, oh, stick it on that sign over there or stick it over here now, you know, in a park or something as well. And so, you know, people using them more on their homes even. I mean, that's a tiny amount compared to street lamps. But there is just always this extra light more and more all the time with the use of LEDs and how cheap they are.

And yes, it's great that they are more energy efficient, but there still needs to be more done. And again, more regulation needed if we're going to protect night skies. I mean, what do you think, Robert? Like, I think you've had a bit, a lot more experience with this with the Royal Astronomical Society over the years as well, right? Yeah, that's right. I mean, we do, you know, we're much more into it than me. Well, actually, the society's been doing this stuff for many years. We even gave evidence to Parliament as far back as 2005, I think it was. And when it was in Greenwich, I remember taking MPs around the site and saying, this is a historic observatory. And by the way, there's the laser beacon from Canary Wharf, even 30 years ago, getting on for 30 years ago, 25 years ago, all this stuff being illuminated. So your points are absolutely well made. And I think, you know, my genuine feel about all of this is nobody is saying make us it is dark. You know, nobody is saying that we somehow want to go to some medieval period with people going around lighting up, you know, lighting up things on torches and so on.

It's nothing like that. But we do need to recognise that this is not just an issue for astronomers, but for the wired environment as well. We work very closely with the charity bug life who look after invertebrates, you know, the sort of creepy crawlies that you might have mixed feelings about, but which are essential for our natural world. And they will argue very, very convincingly that this has a hugely detrimental effect. We talk about the insect apocalypse, you know, the number that not appearing on your carbon, screen, one of the causes could well be light pollution because it confuses invertebrates, higher animals, birds and so on at night. So I think in tackling this, much as my first, you know, my first thought will be, oh God, what's it doing to the skies? Actually, we need to

recognize the bigger problems too and say, you know, if we're getting this wrong, it's something we can fix. And there's a really great point made by Karamaz Foglu, who runs a sort of lighting company that specializes in dark sky places. And he always makes the point. He says, well, this is unique in environmental challenges. Because if you want to get rid of it, you just switch the light off. Easy speaks, yeah. So it's not like CO2 in the atmosphere where it's going to take tens of thousands of years to come down if at all, you know. It's not like plastic pollution where there's enormously complicated solutions. This is one we can do something about. We can redesign lighting. We can switch things off. You know, we can make a more conducive night, you know,

and I think actually perhaps there needs to be a sort of cultural thought about well, darkness isn't always bad, you know, actually, you know, that we need it for good sleep and all of those things too. So, and to, you know, to reference, I think about my sort of childhood memories of dark skies or even those when I was younger and I remember going on a holiday to Dorset with my family and being in a caravan site and looking up and seeing the Milky Way probably for the first time, you know, and I wonder how easy that is to do there now. I also remember, I suspect this is probably still pretty good, going to Southern Africa as long as 2001, 2002 because there was a guide for the solar eclipses that were there.

looking up at a pristine sky. Now, the southern hemisphere's skies are brighter anyway, but seeing those in this totally unfettered environment, it's absolutely special. And you just think, well, yes, in the UK, we've got little issues like weather that block it a lot of the time and clouds. But wouldn't it be great to just assume that this is everybody's childhood memory, if you've got good vision, you can look up and see that.

So, yeah, so we can fix the problem. I think there is a sort of more hopeful message on ground-based light pollution, at least, that we can bring in. OK, so we've talked a lot about the impact on our night sky, but what can we actually do about keeping it dark? Andy Lawrence is the Regis Professor of Astronomy at the University of Edinburgh and works at the Royal Observatory, Edinburgh. A few years ago, he published a paper called The Case for Space Environmentalism,

and I wanted to know what solutions are out there and what exactly is space environmentalism. It means trying to be good stewards. It's treating space the same way we try to treat the atmosphere around us, the land, the forest, the sea. We should look after the place we live and not destroy it while we're trying to do the things we want to do. And I very much prefer this term environmentalism to two others that are common. Everybody talks about space sustainability. And I don't like that word because it sounds a bit like, greenwashing to me. You think, what is it you're trying to sustain here? And some people on the other hand have started to talk about space ecology. I don't really like that either because it's not really true. Space isn't really an ecosystem, but it is an environment and we are systematically contaminating it, polluting it, degrading it. That's probably the best word. And we should stop doing that. Yeah, and I guess it comes down to that. We're having those conversations about

exploiting different environments as well and I guess that needs to come into the conversation of when it comes to space as well. So what would you say are the things as an astronomer, if astronomers could rule the world, what would they do to get rid of light radio pollution or anything to help conserve that environment that is space? Oh, scary question.

Well, you can't stop light pollution. completely and we wouldn't want to. Like all other environmental concerns, it's a question of balance because we do want to build the economy, do things in space. Space is very important to us for communications, for monitoring the climate, for doing the science we want to do as astronomers. What we need is to set technical standards on how bright satellites can be and more importantly to me, and this is a point a lot of people miss, how many new needs. to do a particular job. I would say no individual satellites should be bright

in the seventh magnitude, and you should limit the number you need to do a particular task. Also, and this is much harder, I'd love it if there could be international cooperation, why we need so many competing systems to do the same thing. The Chinese are going to launch their mega constellation

because they don't want their people using Starlink, etc. and so that's the way of the world and it's very difficult to stop. But on the other, there's only one internet. We all use the same protocols, TCP, IP, etc. And you might hope in principle that you could set out one fleet of satellites to provide or improve internet access to the world. And to do this, you don't need vast numbers of extremely big satellites. We should be investing more in optical fibre.

in undersea cables, in cell phone masks in remote places. There could be a complete infrastructure of different types of method, which rationally would provide internet access to wherever we needed. Yeah, and it's like taking a step back, isn't it, just to assess what could be done differently. It's a question on efficiency as well. And so when we look to dark skies, what are governments doing?

to try and protect that already? At the moment, over the preceding years, absolutely nothing. Space activity is heavily regulated in all sorts of ways, but there's been no rules and no regulations about how bright a satellite is allowed to be. It's certainly in the optical. This is also true. Radio world controls which bands, which frequencies you can use and so on,

and that's very well developed. But again, not in terms of brightness. So there's been nothing. So that's starting to come. There's a reasonable international consensus among astronomers who suggest that individual satellites are kept fainter than seventh magnitude. And obviously, that's less than naked eye brightness. It's the magnitude at which things get really bad

with the Rubin detectors and other similar, very sensitive detection systems. At the moment, there's a new EU Space Act underproposal, which the Royal Astronomical Society, by the way, It responded to the consultation that's underway there. Even though we're not in the EU, it matters to us. It's all a global problem. But this is the first time that some governmental or intergovernmental body is trying to put into law some sort of requirement and brightness. So it mentions in Article 73 the 7th magnitude requirement.

It's not really hard-nosed enough, I think, but it's an amazing start. And, of course, the problem is that the US government want none of it, let alone the Chinese, but the EU have made a start. And individually, quite a few governments have taken notice at the key United Nations committee, which is copious, the Committee on the Peaceful Use of Outer Space. There's now, I think, called the Group of Friends. There are 17 nations that got together and forced a standing agenda item on dark and quiet skies at that UN forum.

So that's slowly having an impact. The UK Space Agency are very keen and looking at how we deal with these problems. But as ever, with law and government, slow as treacle. And how hopeful are you of us being able to solve the problem of space noise within the next decade, a couple of decades?

Or do you think it's going to get worse in that time? That is an extremely good question, is it? But why it's so hard to answer, there is real momentum. Astronomers are very excited about this. The governments are taking us seriously. Regulators are thinking about it. It's discussed at the UN. So that's all very promising.

But on the other hand, the momentum for growth in commercial space is terrifying. So I'm sure you've seen this. There are proposals now for big satellites that deliver sunlight. as a service, just reflect light back deliberately. Data centers in space. Everybody's got their own mega constellation being planned. Which of those tendencies is going to win? And whether or not that bubble will burst, for instance, it may sort itself out. I don't know. One other thing I'd like to squeeze in there, because conversely, a lot of people say, oh, come on, astronomy is not that important, is it? We just suffer some lights in the skies, so what. And I have some sympathy with that,

actually, because compared to climate change or plastic in the sea, it's not that important. It's very important to me in my work, and I love it. But here's the thing. And this gets back to why I talk about environmentalism. Because to me, when you stand it next to climate change or plastics in the sea or biodiversity, etc., I think, oh, this is all the same thing. And it's all the problem of growth. And it's just physics, really, because the more you do, entropy tells us, the more mess you'll make. So either you do less and don't make as much mess or you clean up as you go along, okay?

It's not just astronomy, it's the same problem nearly all of the modern world and that's why environmentalism as a general philosophy is so important. And so a lot of people that listen to the Supermassive podcast are naturally fans of stargazing and the night sky. So what can people do on an individual level to just make things a little bit better? Talk to everybody else and spread the word.

Whenever you have the opportunity to speak to local policy makers, seeing your local MP or MSP or whatever, make yourself known, spread the word. Thank you to Andy Lawrence and this episode is a little bit longer than usual, but I think we've got time for a couple of listener questions. So, Robert, we've had quite a few questions about safety. So there's one here that says, how can we balance the need for dark skies with the need for safety and security,

particularly in cities, which is a great point. And then someone else on Instagram says, what are the obstacles around getting our city lights switched off after, let's say 10pm? It's a tricky balance that. Well, this is a great question. and for once it's a question when I say great, which doesn't mean that I'm struggling to answer it. It often comes up.

There's always going to be that concern about how we think about safety, security, public safety in particular, but also road traffic safety and measures to tackle crime with dark skies. But I think it should be much less of an issue than we tend to think. There's surprisingly weak evidence that brighter lighting does very much to reduce crime. You need some light, obviously, but I think it needs to be smarter lighting. It's not about maxing out the illumination. And to some extent, if you brightly illuminates a brace, you're actually giving criminals the light they need to work. But in any case, tackling light pollution is not about abandoning lighting altogether. It means using good lighting in place

with proper shielding so it doesn't light up the sky as bright as is necessary, not wasting vast amounts of energy illuminating unused spaces. Another facet of that is the colour, where warmer colours are better rather than glaring blues, and avoiding glare overall that dazzles drivers, for example, so that you might have recently heard about the call for a fuller study into the impact of modern headlights on that. As I'm driving myself at night, you know, I'm very aware of that. It's the bright LED headlights and actually can be very, very challenging. So brighter isn't always better. I did recently as well go to a workshop in Newcastle on dark skies, and there was some very interesting presentations there around the fact that you can illuminate road junctions

much more softly than you think. It's not about intensity of the road. If you light the sides the road, for example, just soft lighting on cycle paths. It was much more obvious to drivers what they needed to do than if you just pump up the lumens if you make things as bright as possible. I do nonetheless obviously recognise, you know, I'm a man talking about this stuff. Women have particular concerns around safety and rightly so. And so we do need to bring people with us on this and actually have effective lighting. But I don't think that needs to mean super bright. And equally, I also recognise that we shouldn't be just simply switching it off. We need to find that balance, understand how to make these things work. And in space, the same applies as well

when we talk about the impact on dark and quiet skies of satellite constellations. We are working with the RAS, that is, and other groups are working with those operators with the private companies to try and make the spacecraft as dark as possible. I wouldn't say that's always been successful. We're trying that, but still delivering the services we need. And I think in all of these things, it's about understanding the impact, mitigating it as much as possible. And perhaps sometimes compromising on the service output. But on the whole, it's much more about just reducing the impact and making sure that we do these things cleverly.

And fundamentally, that we still get to enjoy dark skies is that if you ask me what I'd almost describe as a human right to a dark sky or even darkness at night is preserved. And Becky, I think this is a nice one to end on, which is from Karina Seifor, who asks, what's the darkest and best night sky that you've seen anywhere in the world? Ooh, okay, so that's a fun one because I think I'd have to say La Palma

which surprises me because that's in the northern hemisphere. Yes, I am also surprised by that, but okay. But I could see the Central of the Milky Way when I saw the night sky in La Palma and I think the reason was I was on the summit of the mountain there where there is an observatory. For those who don't know, La Palma's in the Canary Islands, so islands just off the west coast of Africa.

And I was on top of the summit of the mountain where you have observatories. And it was a night where we had a cloud inversion Oh, nice. So this is where you're above the clouds. And so the clouds had completely smothered, like, everything below you. So it was like standing on a mountain in a sea of clouds, right? And you just had the night sky above you.

So in the same way that, you know, it's like a really dark day because it's really stormy. And like, we just have one of these in the UK, right? You're like, how is it this dark at midday? I have to put the lights on, right? Because it smothers so much light. The same was true, but in the opposite direction. So I just had the darkest night sky I'd ever seen before. And the thing about La Palma is that it's at an altitude where you don't get like altitude sickness and things like this.

I mean, the best of all of the worlds, basically. And so I still had enough oxygen, you know, for my eyes to appreciate how beautifully dark this was. Because I thought the best night sky I would ever see would be the summit of Mount O'Keyer in Hawaii, except for the fact that it was 4,000 meters. And so my body was like, we're going to conserve oxygen and we're going to take it away from your eyes because you don't need. to detect magnitude 5 stars with your eyes right now and I'm like, but I do, but I do, brain, you know.

And so I think maybe it would be Hawaii for about 10 seconds from the oxygen canister I took a hit from when I was off there. But otherwise, it was definitely, definitely the Palmer. Oh, amazing. And Robert, what about you? I think the darkest skies I've seen in my memory definitely are those ones in Southern Africa. So low altitude, I mean, maybe a few hundred meters above sea level

or something like that, but just exquisite. unbelievable. I mean, anyway, it was a pretty good trip involving a total solar eclipse and lots of amazing what I'd like for in a game part. Yeah, that's my yeah. Rob it in, rob it. Nostalgia's great. But yeah, I do remember seeing things like there's a diacal light really clearly,

which is something you really struggle to see if you're in place like the UK. Absolutely stand out. All of those things just there. And because it was around a total solar eclipse, the moon was new or near new. So you had basically the darker skies, as you can imagine. I don't know where the nearest town or

city was, but it must have been, any source of lighting must have been hundreds of kilometres away. And there it was, just this, the arc and the milky way above our heads. Oh, so good. I think mine has to be Peru, but I spoke about that recently. So everyone already knows that. Again, I'm just playing catch up with you two. Yeah, true. Anyway, shall we finish with some stargazing? I guess. Robert, what can we see in the night sky when we switch off all the lights, please? When we're in that nice, dark place, or not. Well, we're finally going into winter proper in December and the longest nights. And remember the solstice and the shortest days on the 21st.

Winter is coming. 21st of December this year. And so that also coincides with some of those brilliant constellations that we see in the northern hemisphere. So by now, Orion is really obvious later in the evening. It's marking that, you know, it's almost like a Christmas treat, isn't it, Orion coming up over the horizon. And the red super giant beagle juice at top left and the blue supergiant Rigel at bottom right. And then Belatrix and Seif complete this lovely box around the three stars, the belt, and the nebula hangs down from that in the sword of Orion. And it's a real joy to see it from a dark sky.

You suddenly start to lose the shape of it because there are so many faintest stars there. If you pick up a pair of binoculars, you obviously so much more. Above Orion, you've got Origa, the charioteer, the bright star capella there, a clutch of clusters of stars. And then to the top right Taurus with the Hyides and Pliades, which are very obviously the eye. But all of these things look better in binoculars. Gemini, the Twins. Castor, which is a six-star system, and you can resolve it into three of those with a telescope and Pollux. Bottom left, later still, is the brightest star in the whole sky after the sun.

Sirius, and a bit above that is Prasian. And those stars, so I'll read them out in order, hopefully. Sirius, Prasian, Pollux, Capella, Al Debra and Intoris and Rijal, they make up the so-called winter circle around Beetleges. And it's like this lovely signposts for the winter sky, like the summer triangles. I think you'll find it's a hexagon. It's six stars. I know. And hexagin is a hexagon.

It is a hexagon. I like the circle description, too. It's a sort of slightly, it's not a very regular hexagon. So, yeah, but you're right. It definitely has six sides and people do so in the middle. It's a hexagon. We should debate that, shouldn't we? What is the most reminiscent of?

Or maybe it's the winter ellipse or something. But anyway, yeah, the other things to bear in mind in the coming weeks, Jupiter is getting towards its best. It's opposition in January. So it's really bright and high in the sky now. Located in Gemini. That's about as high as it. gets for us. So if you've got a small telescope, do take a look. Very obvious Galilean moons.

Lots of features, weather features in the system. Saturn is just about hanging in there in the southwest as it gets dark and the rings are only very slowly opening up. And if you've never seen Mercury, it's a good time to do that because the first two weeks of December it will be very, very visible in the morning sky. So this time you know, it doesn't mean that early either, 6 a.m. or something, it'll be low in the southeast. And you need to use something like Stellarium to find it. And finally, the Gemini's meteor shower is on this year and well worth a look and it's often one of the strongest showers of the year so theoretically 150 meteors an hour but by the time you think about how

many you can actually see you might get a hundred an hour which is really strong if you've got perfect conditions yeah a hundred an hour is still like more than one a minute it's really good yeah I mean let's see you're like no hundred I'm like oh my god we shouldn't quibble should be exactly right yeah and I think with this one it's like unless it's an absolute meteor storm of a thousand meteors an hour I'm not bothered it I know I know it's That tension, isn't it, hide for not hide? It's amazing. Get out and try and see the Gemines. They're on a Saturday this year.

Go see the Gemini. Go see the Gemines. With that one, it's a really strong shower and we often don't know about it. I suspect because it's in the middle of December. It's in the UK at least, you've got often cloudy wet weather. But if it's clear, get out and have a look on the night of the 13th to 14th to December or maybe either side. It's a really strong shower. I do have a memory again, you know, for what I was teaching about 30 years ago of going out with the student

and looking, and one of the GCSE projects is with adult learners was to plot a meteor shower properly and it worked brilliantly. And it's the only time I've seen it really well because it's so often cloudy. But if it isn't, it'll be great. But you need to look before 2 o'clock in the morning when the moon rises, which I know is a challenge asking you can go to bed by 2 a.m. But I think a realistic one. This is why the geminets is so good. It's like, you've got to go out in an evening and it's on a Saturday this year. Exactly.

Yeah. Where something warm. So, yeah, all of that really applies. I was about to say I won't be doing anything else that weekend but I will because I'll be watching the Eres Tour documentary so that's a lie. So Paul's Taylor Swift everyone and go watch the Geminid's each other. Is that the release date?

Well, you can kind of combine the two right. You can watch that and then go out. Look at the stars. It's going to be a big night for Becky, basically. It's what she's trying to say. It's such a big night. Well, I think that's it for this month. We'll be back with a bonus episode in a few weeks time

to answer more of your questions and we'll be doing our usual Christmas gift roundup for the space lovers in your life. And then our final episode of the year is the one that we've promised that we would do and it's going to be on time travel. My time travel beyond that episode

because it's going to hit my head. It's good to have light topics, isn't it? Becky's literally putting her head in her hands. It's going to be fine. I basically don't have the vocabulary to describe what needs to be described in time travel. I get so tied up in.

not in terms of what I'm saying. I'm just like, oh, this is so difficult. I mean, Becky may be putting her head and hands. I'm sitting there thinking, thank God, Becky's on this call. Anyway, time travel. We will do it for you. You have requested it so many times. Also, contact us if you try some astronomy at home. Are you in a dark sky area? Let us know. Please brag about how great your sky is. Tell us what you can see. It's at Supermassive pod on Instagram or you can email. your questions or night sky amazing images

to podcast.orgas.ac.org and we'll try and cover any questions in a future episode. But until next time everybody, happy stargazing.