PBS News Hour

AMNA NAWAZ: Astronomers around the world are calling for international agreements to limit the spread of satellite constellations in space, warning that the light pollution they create damages vital scientific work.

In Britain, the government is also being urged to impose new planning regulations to stop the alarming loss of the nation's dark skies.

Special correspondent Malcolm Brabant reports from Southern England.

MALCOLM BRABANT: After one of the worst British summers in recent memory, a September sunset of this caliber is enough to make anyone salsa like no one is watching.

But in increasingly urbanized Britain, the same can't be said of our night skies.

I'm using red light because I want to protect my night vision and also to minimize light pollution, as I'm about to do some time-lapse videos of the night sky.

It's pretty cloudy tonight, but I can still see the stars, although the clarity is nothing to make a song and dance about.

Images of the twinkling heavens are tainted by the tinge of light pollution from the city of Brighton.

This is a fair representation of the state of the skies above much of the U.K. DAN OAKLEY, Managing Director, Darkscape Consulting: We're seeing roughly a 10 percent loss of our skies over the last 10 years.

We're slowly losing access to our dark skies.

Nature's suffering from it as well.

They're losing their dark skies, and that's a really key, important thing to lose for us.

MALCOLM BRABANT: Dan Oakley is a dark skies consultant working to reduce light pollution.

DAN OAKLEY: A dark sky is something that connects humanity to the wider universe, really, and being able to stand under a dark sky means you can kind of look at yourself in the mirror and try to figure out where you came from, ask those big existential questions of life, the universe and everything.

MEGAN EAVES, Editor, "Nightscape": I grew up in the Southwest part of the U.S. in a place and time when there wasn't as much light pollution.

MALCOLM BRABANT: Megan Eaves swapped the darkness of New Mexico for London's bright lights 13 years ago.

She's the editor of "Nightscape," a quarterly magazine committed to reclaiming starry, starry nights.

MEGAN EAVES: It's just such a fundamental part of who I am and also a part of who humans are.

All of our art and our music and films throughout history have been inspired by the night sky.

MALCOLM BRABANT: Dark sky activists insist there are compelling health reasons to fight light pollution.

MEGAN EAVES: Light at night disrupts our circadian rhythm, which is what produces the hormone melatonin, which impacts our sleep cycle.

It can result in all sorts of mental health issues, and it can lead to all sorts of different illnesses.

WOMAN: And great news.

All systems are go for launch, so let's watch as Falcon 9 takes our 22 Starlink satellites into space.

MALCOLM BRABANT: The final frontier of light pollution.

ROBERT MASSEY, Deputy Director, The Royal Astronomical Society: There's great concern in the global astronomical community about the impact of satellites in low Earth orbit and what that means for our science.

MALCOLM BRABANT: Leading astronomer Robert Massey and his peers want governments to pay attention.

ROBERT MASSEY: We're effectively in a paradigm shift.

We have gone from having a couple of thousand of these in low Earth orbit a few years ago.

What we now have is a number which is 6,000 or 7,000 and rising rapidly.

MALCOLM BRABANT: And most of those are Starlink satellites owned by Elon Musk.

The Ukrainians are reliant on them as they try to drive Russian forces out of their territory.

ROBERT MASSEY: It's not inconceivable that we could see hundreds of thousands of satellites in that region of space above the Earth.

WOMAN: Starlink satellites operate in low Earth orbit, which enables the delivery of high-speed low-latency Internet to people living in remote and rural locations around the globe.

MALCOLM BRABANT: Satellites reflect sunlight.

This video shows a train of satellites shortly after their release into orbit.

ROBERT MASSEY: We rely on pointing very sensitive telescopes at the sky, looking for faint objects.

And what happens with satellites crossing the field is that you get a whole series of streaks.

An awful lot of data is lost, and that science is compromised.

MALCOLM BRABANT: But satellite companies are trying to minimize light pollution from space, as Dr. Bruce Cameron from the Massachusetts Institute of Technology explains.

DR. BRUCE CAMERON, Massachusetts Institute of Technology: So they have tried applying new coatings on the outside which either absorb light or reflect light back into space.

They have tried sunshades, meaning shading the satellite from some of that inbound sunlight that is then reflected back to Earth as light pollution.

MALCOLM BRABANT: Space has become the new Wild West.

China is talking of launching a constellation of 13,000 satellites with the potential to expand even further.

As light pollution expands across Europe, dark spaces are ever harder to find.

This is Beddgelert in North Wales.

The music of the river and perfect starlight helped convince Emma Sloan and her husband to buy this hotel in a valley where, even on a cloudy night, shooting stars magically appear.

EMMA SLOAN, Hotel Owner: It makes you so aware that there's something bigger out there, but so much larger than us.

It also connects you, I guess, with whatever energy the sky is.

And it also gives me a sense of, this is how the world should be.

MALCOLM BRABANT: Elsewhere in Britain, people head to dark sky reserves in national parks, like this one near the South Coast.

Sunsets can be spectacular, as can the night.

This is the Milky Way above a feature called Devil's Dike.

If you look carefully you can just see the galaxy above the windmill in a time-lapse filmed just 10 miles away, demonstrating that the purity of darkness is at risk from encroaching development, as Britain builds new towns to house its growing population.

DAN OAKLEY: It's made worse by bad lighting choices and bad installations.

So what we can do, as communities and national parks and government, is to make sure that we have good guidances to help people put up the right kind of lighting at the right place at the right time.

MALCOLM BRABANT: Like this example, where the light is directed downwards, where it's needed, not upwards, where it's not.

MEGAN EAVES: The thing that gives me the most hope is that light pollution is actually the easiest form of pollution to solve.

We already know how to solve it.

We simply light better, light smarter, light more efficiently, waste less, and turn off lights that we don't need.

MALCOLM BRABANT: Once in a rare super blue moon, the power of the solar system cuts through the haze.

This phenomenon took place nearly a month ago and won't appear for another 14 years.

What will light pollution be like then?

For the "PBS NewsHour," I'm Malcolm Brabant on Britain's South Coast.