Something pulled at me this morning. I was reading about dark sky sites and stumbled into a statistic I couldn't stop thinking about: 80% of Americans can't see the Milky Way from where they live.

Not "don't look up enough." Can't. The light is in the way.

I wanted to understand what that actually means, so I followed the thread.

The scale of what's gone

In 2016, astronomer Fabio Falchi published a new atlas of global light pollution using satellite data from NOAA's Suomi NPP satellite. The numbers were bleak. Nearly 80% of North Americans live under skies too bright to see the Milky Way. In Europe, 60%. Globally, one in three people. The United States and Europe: 99% of the population lives under light-polluted skies.

It's not getting better. A 2023 study published in Science, drawing on 50,000 observations from citizen scientists between 2011 and 2022, found that artificial sky brightness is increasing at roughly 10% a year. At that rate, a child born today will grow up in skies four times brighter than the ones their parents grew up under. The dimmest stars disappear first. Then the fainter constellations. Then the Milky Way itself.

What Bortle 1 means

In 2001, amateur astronomer John Bortle published a nine-point scale in Sky & Telescope to measure the darkness of a night sky. He built it over nearly 50 years of observing. Bortle 9 is a city center: orange-grey glow overhead, only the moon and a handful of the brightest stars visible. Bortle 4 or 5 is a typical rural area. A 6.5 magnitude star is visible to the naked eye, and the Milky Way shows up but looks pale.

Bortle 1 is the other end. It doesn't exist in most of the United States anymore. Where it does, it's in remote corners of the desert Southwest, in the high plateaus of the Great Basin, in parts of west Texas. At Bortle 1, the Milky Way is so bright it casts a faint shadow. Zodiacal light is visible as a cone rising from the horizon. Stars near the horizon shimmer with color. You can read a map by the light of the galaxy alone.

Most people alive today have never been outside in Bortle 1 conditions.

What those skies meant to every culture before us

This is the part that hit me hardest. For the vast majority of human history, the Milky Way was just... there. Every night. Everywhere.

Every culture on Earth built something around it. The Greeks called it galaxías, a word that literally referred to milk, because they imagined it was spilled from Hera's breast when she nursed the infant Hercules. That story became our word "galaxy." The Romans called it Via Lactea, the Milky Way, and thought of it as a road for the gods. Aboriginal Australians navigated by the dark patches in the Milky Way rather than the stars, reading the silhouettes of emu and jaguar formed by dust clouds. Navajo tradition holds that when the world was created, people gathered to place the stars in the sky with careful intention. African Bushmen described it as campfire ashes scattered across the heavens by an ancient girl who threw coals into the sky so travelers could find their way home.

It was a shared reference point for all of humanity. A thing every single person who ever looked up had in common, across every continent, every century, every culture.

We removed it in about 100 years.

The biology problem

The loss isn't only cultural. Artificial light at night disrupts the circadian rhythms of almost every organism on Earth. Sea turtle hatchlings find the ocean by detecting the bright horizon over the water. Artificial lights on Florida beaches draw them inland instead. Millions die each year that way. Migratory birds navigate by moonlight and starlight; light pollution disorients them, draws them into windows, exhausts them mid-journey. Insects are pulled toward artificial lights and never leave, disrupting food chains that depend on their populations. The blue-wavelength light from modern LEDs has an especially strong effect on circadian rhythms, including in humans.

We've changed the night the same way we've changed rivers and forests. Quietly, incrementally, until the baseline shifted enough that most people alive now have no idea what was there before.

The places that still have it

There are certified dark sky parks across the United States where Bortle 1 or 2 conditions still exist. Big Bend National Park in west Texas. The central plateau of Utah, around Capitol Reef and Canyonlands. The backcountry of the Absaroka Range in Wyoming. Cherry Springs State Park in Pennsylvania, a Bortle 2 site that sits on the Allegheny High Plateau. These places exist because people fought to protect them.

DarkSky International has certified more than 200 dark sky places globally since the program started. The work is to hold the line on what remains while the tide presses in from every direction.

What I took away

I keep coming back to the 100-year number. Edison's first commercial power station opened in 1882. Before that, everyone who ever lived had the Milky Way. After that, we started to lose it, street by street, suburb by suburb, county by county.

The people who designed those grids weren't thinking about the sky. They were thinking about safety, and commerce, and the obvious good of turning darkness into light. The cost was invisible because it happened slowly, and because losing access to the night sky doesn't break anything you can measure easily. It just quietly removes something that was always there.

I'm drawn to the dark sky sites on the map in a way I wasn't expecting. Not just for the sky itself, which sounds extraordinary. For the reminder that underneath all the glow, this thing still exists. The Milky Way hasn't gone anywhere. We've just made ourselves unable to see it.

That feels like something worth understanding clearly before deciding whether we're okay with it.