Science Friday - Reconnecting with the night sky and reining in light pollution

Episode Date: July 10, 2026

What happens when the skies are no longer dark at night? Writer Craig Childs biked from the brightest night sky, to the darkest, to find out what we lose when the lights don’t go out. He joins Host Ira Flatow to talk about his book “The Wild Dark,” our SciFri Book Club pick for July and August. Plus, astronomer John Barentine fills us in on DarkSky International’s latest report, “Artificial Light at Night: State of the Science 2026.” Read an excerpt from “The Wild Dark: Finding the Night Sky in the Age of Light.”  Guests: Craig Childs is the author of “The Wild Dark: Finding the Night Sky in the Age of Light.”  Dr. John Barentine is an astronomer and principal consultant at Dark Sky Consulting, LLC Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Follow our show on Instagram, TikTok, Facebook, and Bluesky @scifri and sign up for our newsletters. Got a science question that’s keeping you up at night? Call us: 877-472-4374 Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hi, I'm I Refleto, and you're listening to Science Friday. One of the summer's greatest pleasures, at least for me, happens when the sun goes down. I grab my lawn chair, my binoculars, maybe even set up my telescope, and head outside to look at the night sky. And on a really good night, out in the countryside with no moon, I might see the Milky Way, or maybe Orion's belt, even the stray meteorite. But you know what? Over the years, it seems like. like I'm seeing fewer and fewer stars and planets. Light pollution has dimmed my sky view, and I'm not alone. Scientists have estimated that more than 80% of the world's population, more than 99% of people in the U.S. and Europe, live under light-polluted skies. That light in the night is called

sky glow, and it is ruining our nighttime views. My first guest set out on a bicycle to document the sky glow and to find out how artificial lights at night are affecting the sky, the environment, and us. Craig Childs is a writer. His latest book is called The Wild Dark, finding the night sky and the age of light. And it's our SciFry Book Club pick for July. You can read right along with us, head to ScienceFriiday.com slash book club. Craig, welcome to Science Friday. Oh, thanks for having me, Ira. You're welcome. Let's talk about your trip. Give me the ABCs of what you did. Well, I started in Las Vegas on the Las Vegas strip with a bike loaded for for 10 days of backcountry and a companion who was equally loaded up and we biked out of the city and headed for the

darkest place we could find. Where did you start your trip and where were you going? Well, we went we went due north out of out of Vegas into the, into the Mahave Desert to the desert wildlife refuge and just out on these rough roads for 200 miles to basically see how the night would change, what kind of sky we would get for nine sequential nights going into the desert. And why a bike? Why not hop in a car? Well, you know, a bike is the right pace. If you're driving, you would get to where we're going too quickly. And I wanted to see that transition. I wanted to see each night, it'd become entirely different. And walking would be too slow because I don't think I would

have really seen that transition. So biking was the right pace to get a different sky so that each night we're looking at a completely new experience. And we're going across the new moon. So we're missing any moon glow and we're seeing just the full clear night sky. Where did this idea come from, Craig? What got you interested in this? Well, it seems like everything I'm writing about has a night sky in it. There is always some reference to stars, planets, because it's really half the experience of being in the world. And I'm outdoors most of the time. So I've got this focus on the night, and I've lived in bright places and mostly in dark places.

but I find that it's such a powerful experience to see a full set of stars that I wanted to know what it's like to go from brightest to darkest and how that transition affects you, how it affects your eyes, your body, your experience in general. It can be pretty spooky, you know, that total change of atmosphere. Yeah, you're looking at infinity, which, you know, during the day you're not. And during the day you're looking at sky and during the night you're looking at space. Right. And so how did you pick your stops where you were going to stop?

Where we ran out of energy. Where we just, I was using what's called the Bordal Scale, which is a nine-level scale from nine being the brightest sky, which was the Las Vegas trip, to one being the darkest sky that you could find. And so each night it really was, you know, we would bike into the dark and we would just finally go, okay, that's far enough. Stars are coming out. Let's drop here. What's a Bordle? Is that named after somebody? Yeah.

It's a perfect astronomy word. I know. It's a great word. It's somebody's name, John E. Bortle, who's an amateur astronomer focuses on comets. and he needed a scale that didn't use a device. There was a naked eye scale where people could explain what kind of sky they were in. And so he just set up this scale from going from the brightest to the darkest. And I was drawn to it partly because of the name.

Because it does. It sounds like something hurling through space. Right. It really does. Now, I remember being in Las Vegas once, and there was a national park outside there. and there was an astronomy viewing club in the park, and the contrast between the light in Las Vegas

and what was going on like 20 miles away was amazing. Did you find that also? Oh, yeah, yeah. Every night was remarkably different, and that's what I didn't know if that would happen or not. You were seeing so many more stars night by night, and so you're watching this transition, even the second night.

I mean, the first night, when we got out of the city, it's still that ivory glow of, you know, macular degeneration coming out of the city. But after that, you know, you start picking up more and more stars and even 20, 40 miles out of the city. We were getting a pretty nice night sky.

Right. And so what did you learn about the night sky? on this trip? I learned that it's the transition that really matters, that going to a dark place, you want to be there at dusk, you want to watch the stars come on, because then your eyes really adjust. Because by the end of this, I got to the darkest sky that I've ever seen. And I live in a Bordal one, in Colorado. And I've been way out in the Otacama Desert in South America, which has, you know, most of the big telescopes. And so I've seen those great dark skies,

but it was very different actually going through the transition. And by the end, seeing the most spectacular sky I've ever seen, which was not because the sky was any more full of stars. It was because my eye, I was adjusted. My sense of light and darkness had changed. So it made me realize that it's, It's not just about artificial light, but it's also about your own perception and your own readiness to look up and watch the sky.

And you sort of lose track of time, don't you? Oh, yes. I prefer being out there where you lose the name of days and numbers, and you're just going by the rhythm of sunrise, sunset, night, day. Because that's what our bodies are made for. Right. You know, we evolved for that, not for the world we live in now. This is a, the human world with light is, is not one we're really set up for. Our circadian rhythm is based on the light and dark.

So we really need both of them. We have to take a quick break, but don't go away. More on this when we get back. I want to bring on another guest to tell us more about the state of our night skies. John Barrontyne is an astronomer and principal consultant at Dark Sky Consulting. Welcome to Science Friday. Thank you for having me on the program, Ira. You're welcome.

I know you've been working for a long time on trying to keep skies dark at night. Are there any bright spots, so to speak? Oh, there are always metaphorical bright spots to be found. I'm really heartened by the work that a lot of the advocates are out there doing in their communities here in America and elsewhere. there are whole countries now in some parts of the world, for example, Mexico and France that have decided that light pollution is environmental pollution and it's serious and it should be built into their environmental laws. And we're starting to see some results of that in the measurements that we're making. But at the same time, we're a long way from solution to this problem. And in many

respects, it gets worse by the year. I want to talk about a report called artificial light at night, state of the science 2026. The report mentions data centers in the sky. Stuff people don't want in their backyards, a potential new addition to sky glow up there orbiting the earth. Tell us about that. Yeah, I'm concerned about this as sort of transferring from one environmental problem to another, which on the surface sounds pretty great. A lot of people are concerned about data centers on the ground, impacting land use and water and having these other negative consequences. And so the thinking as well, maybe if we just put them in orbit, we can deal with a lot of those problems. The concern is, though, is you have to generate a lot of electricity to run a data center, whether it's on Earth or in space.

In order to do that, you have to put giant solar panels on them. And we know from observations of the very many, now in the tens of thousands of artificial satellites orbiting the Earth, that these large reflective surfaces make them bright in the night sky, especially in twilight around evening and in the morning. So if we put these vastly larger and highly reflective objects into orbit, and maybe as many as a million of them, we're looking at a radical transformation of the night sky, unlike anything that we have seen in human history.

I cannot imagine a million new satellites with solar panels on them orbiting. Right, the least of which is that it's making things up there very crowded, and the chance that we will have some problems with space debris and possibly even closing off space to future access for some indefinite period of time is a very real concern. Now, the report also calls out LED lighting. It's so cheap, relatively speaking, compared to incandescent, that more people are leaving more lights on, right?

That's our hypothesis. It seems to be backed up by data. And for the reasons that you mentioned, it's cheap, it's convenient. People think there are no consequences to its use. So why not put more of it out into the world? But I have to be clear at the same time that LED has a lot of really great characteristics that if it were used correctly and consistently, I think it could solve this problem of light pollution definitively. But we're not using it very well. And we're using too much of it. and we're putting out more light than we need, et cetera. And all of these things add up, I think, to help explain why we're seeing white pollution taking off at such a quick rate around the world. You know, I noticed this spring that a few people are putting signs out in their neighborhoods asking people to turn off their lights at night from migrating birds. This seems like a relatively new development. It's the idea of having these switch-offs for birds.

It's been around now for, I would say, on the order of maybe 15 years or, or so, and it's happening here in Europe and other places. And it's really beneficial to the birds during migration season. So if we could switch off some of those lights during their migration, we'd really be doing them a favor. But then if people start realizing how much excess light we're using, maybe it's not just a special period of time in the year, but they think, you know, do these lights need to be on all night anyways? Right. And it would have a lot of beneficial effects for other organisms besides birds if we dealt with the problem more broadly, rather than just, you know, a couple of weeks in the fall, for example.

Right, right. I want to address this question to both of you because it's something I'm very interested in, and that is Dark Sky International has certified dark sky places in the U.S. and around the world, lots of parks, reserves, even urban night sky places. Have either of you been to dark viewing locations? I've seen some ads for weekend retreats to visit, even. Well, I live in a dark, Sky Community, a town of about 500 in western Colorado near the Utah border. So almost every night since the end of February, I've been sleeping outside here. So I'm in it, and it's real.

It's a sweet spot. John, have you ever been to one? Yes, I've been to many of them, not only here in the U.S., but in other parts of the world. and I have seen evidence in certain places that these designated locations are driving a tourism economy. It's still small relative to other kinds of tourism, but it does appear to be growing. And I was also heartened to find that many of the conservation professionals that work in these places at parks and nature reserves have really taken to heart the messaging around dark skies and how beneficial it is for the ecological world, probably even for humans, and are incorporating that into their practice, whether or not there's a law necessarily that governs it or requires these changes for the benefit of the dark sky. The conservation and lane management world has very definitely embraced these ideas.

And, of course, if there is money to be made in tourism, perhaps we'll see more of these dark sky tourist places. That's the hope. And it's really growing by leaps and bounds. The organization recently certified its 250th place in the world. And the land area, if you added up all up, is the size of a moderately sized country. But of course, you know, the world is a much bigger place. We still have a lot of inroads to make. But I'm, again, I'm seeing some really encouraging science of progress. Well, give me, John, your top pick of where should I go? You've been to these places. That's like asking which of your children is your favorite, right? I mean, there are a lot of them, and my answer is always, you know, whichever one is closest to you, because you're guaranteed to have an experience. It's probably different than anywhere else that you've been. Maybe if I had to pick one, I would choose the Grand Canyon, Grand Canyon National Park here in Arizona, where I live, which is spectacular by day, but it takes on an otherworldly quality.

at night that I can't quite put words to. And standing at the edge of the canyon at night by myself once several years ago in, you know, complete silence and seeing the Milky Way wheeling overhead was something I will never forget. It is really awesome, and is it not? Let me ask both of you, any quick fixes to the light pollution problem that you would suggest, what can I do? Or is this a thing that needs to be solved through government action? Well, I think it's on a lot of different scales because there's a scale of just your lights where you live,

like coming through your window. I live off-grid and for years we've kind of run low on electricity in the winter and we turn to oil lamps. And it's a really nice thing to have to adjust. your own life to the cycles of light going on around you. So on that scale, there's a lot you can do yourself about, you know, changing your outdoor lights so that they're not shining upwards and not shining lights out your window and paying attention to where your light goes personally. So I think on a one-on-one level, we can make changes.

Good to hear. That sounds hopeful. We have run out of time. I'd like to thank my guest, John Barrontyne, astronomer and principal consultant at Dark Sky Consulting. Craig Childs is author of The Wild Dark, Finding the Night Sky in the Age of Light, and it's our SciFry Book Club pick for July.

Read it with us. Head to ScienceFriety.com slash book club to join our community. This episode was produced by Annette Heist. Do you want to help out the show? tell your friends, your neighbors, your car mechanic about SciFRI. Help us out. Spread the love. And thank you for listening. I'm Ira Flayde.