Reconnecting with the night sky and reining in light pollution

IRA FLATOW: Hi, I’m Ira Flatow, 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 a stray meteorite.

But you know what? Over the years, it seems 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 US and Europe, live under light-polluted skies. That light in the night is called skyglow, 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 in the Age of Light, and it’s our SciFri book club pick for July. You can read right along with us. Head to sciencefriday.com/bookclub. Craig, welcome to Science Friday.

CRAIG CHILDS: Well, thanks for having me, Ira.

IRA FLATOW: You’re welcome. Let’s talk about your trip. Give me the ABCs of what you did.

CRAIG CHILDS: Well, I started in Las Vegas, on the Las Vegas Strip, with a bike loaded 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.

IRA FLATOW: Where did you start your trip, and where were you goin?

CRAIG CHILDS: Well, we went due north out of Vegas, into the Mojave 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.

IRA FLATOW: And why a bike? Why not hop in a car?

CRAIG CHILDS: Well, 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.

IRA FLATOW: Where did this idea come from, Craig? What got you interested in this?

CRAIG CHILDS: Well, it seems like everything I’m writing about has a night sky in it, that 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.

IRA FLATOW: It can be pretty spooky, you know? That total change of atmosphere.

CRAIG CHILDS: Yeah, you’re looking at infinity, which, during the day, you’re not during the day. You’re looking at sky. And during the night, you’re looking at space.

IRA FLATOW: Right. And so how did you pick your stops, where you were going to stop?

CRAIG CHILDS: Where we ran out of energy, where we just– I was using what’s called the Bortle scale, which is a nine level scale from 9 being the brightest sky, which was the Las Vegas Strip, to 1 being the darkest sky that you could find. And so each night it really was– we would bike into the dark, and we would just finally go, OK, that’s far enough. Stars are coming out. Let’s drop here.

IRA FLATOW: What’s a Bortle? Is that named after somebody?

CRAIG CHILDS: Yeah.

IRA FLATOW: It’s a perfect astronomy word.

CRAIG CHILDS: 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, that 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 hurtling through space.

IRA FLATOW: Right, it really does. Now, I remember being in Las Vegas once, and there’s 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?

CRAIG CHILDS: Oh, yeah, yeah. Every night was remarkably different, and that’s what I didn’t if that would happen or not, that 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 macular degeneration coming out of the city. But after that, 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.

IRA FLATOW: Right. And so what did you learn about the night sky on this trip?

CRAIG CHILDS: 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 Bortle 1 in Colorado, and I’ve been way out in the Atacama Desert in South America, which has 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 was adjusted. My sense of light and darkness had changed. So it made me realize that 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.

IRA FLATOW: And you sort of lose track of time, don’t you, when you’re out there.

CRAIG CHILDS: 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, those– because that’s what our bodies are made for. That’s–

IRA FLATOW: Right.

CRAIG CHILDS: –we evolved for that, not for the world we live in now. The human world with light 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.

IRA FLATOW: 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 Barentine is an astronomer and principal consultant at Dark Sky Consulting. Welcome to Science Friday.

JOHN BARENTINE: Thank you for having me on the program, Ira.

IRA FLATOW: 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?

JOHN BARENTINE: 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.

IRA FLATOW: I want to talk about a report called Artificial Light at Night– The 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 skyglow up there orbiting the Earth. Tell us about that.

JOHN BARENTINE: Yeah, I’m concerned about this as a 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 is, 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. And in order to do that 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.

IRA FLATOW: I cannot imagine a million new satellites with solar panels on them orbiting. You know?

JOHN BARENTINE: 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.

IRA FLATOW: 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?

JOHN BARENTINE: 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 light pollution taking off at such a quick rate around the world.

IRA FLATOW: 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 for migrating birds. This seems like a relatively new development.

JOHN BARENTINE: 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 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, do these lights need to be on all night anyways. 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 a couple of weeks in the fall, for example.

IRA FLATOW: 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 US and around the world. Lots of parks and 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.

CRAIG CHILDS: 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.

IRA FLATOW: John? You ever been to one?

JOHN BARENTINE: Yes, I’ve been to many of them, not only here in the US 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 had 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 land management world has very definitely embraced these ideas.

IRA FLATOW: Hm, and of course, if there is money to be made in tourism, perhaps we’ll see more of these dark sky tourist places.

JOHN BARENTINE: That’s the hope, and it’s really growing by leaps and bounds. The organization recently certified its 250th place in the world, and–

IRA FLATOW: Wow!

JOHN BARENTINE: –the land area, if you add it up all up, is the size of a moderately sized country. But of course, the world is a much bigger place. We still have a lot of inroads to make. But again, I’m seeing some really encouraging signs of progress.

IRA FLATOW: Well, give me, John, your top pick of where should I go. You’ve been to these places.

JOHN BARENTINE: 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 whichever one is closest to you because you’re guaranteed to have an experience that’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 complete silence and seeing the Milky Way wheeling overhead was something I will never forget.

IRA FLATOW: It is really awesome, 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?

CRAIG CHILDS: Well, I think it’s on a lot of different scales because there’s the scale of just your lights where you live light 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 we– and it’s a really nice thing 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 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.

IRA FLATOW: Good to hear. It sounds hopeful. We have run out of time. I’d like to thank my guests John Barentine, 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 SciFri book club pick for July. Read it with us. Head to sciencefriday.com bookclub 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 Flatow.

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