Why they matter, and what protects them
Badlands National Park was certified an International Dark Sky Park in July 2026. It is 53 miles from Rapid City, and most people alive have never stood under a sky that dark.
What light pollution is
The National Park Service defines it as any adverse effect of artificial light, which includes sky glow, glare, light trespass, light clutter, reduced visibility at night, and wasted energy. More than 80% of the world, and almost every city and urban skyline in the United States, sits under it.
What it does to wildlife
Artificial light at night disrupts predator and prey relationships, reproduction, feeding, habitat selection, navigation and migration. Light from cities pulls migrating birds off course, and they collide with lit buildings or circle them until they are exhausted. Sea turtle hatchlings are drawn inland, away from the ocean.
What it does to people
Artificial light at night interferes with natural sleep cycles. Chronic sleep disruption is associated with raised blood pressure, exhaustion and depression. The research on longer-term effects is active, and the sources below are the place to read it rather than a summary here.
Lighting that does less harm
DarkSky International and the Illuminating Engineering Society jointly publish five principles for responsible outdoor lighting. Light that follows them is:
- Useful. It has a clear purpose, and the effect on the surrounding area, including wildlife and habitat, has been considered.
- Targeted. It is shielded and aimed downward, so it reaches only where it is needed and does not spill past that.
- Low level. It is no brighter than the task requires.
- Controlled. Timers, dimmers or motion sensors mean it is on when it is needed and off when it is not.
- Warm colored. It limits shorter wavelength blue and violet light to the least amount needed.
None of this is about switching lights off. It is about light that is aimed at the ground rather than the sky, which usually costs less to run as well.
What 7,500 stars actually looks like
The Park Service says visitors to the Badlands are exposed to more than 7,500 stars on a given night. That figure is worth understanding rather than repeating, because it is not what anyone sees at a glance.
Around 9,100 stars are bright enough for the naked eye across the whole sky, north and south together. From one place on Earth only half of that sky is ever above the horizon, so roughly 4,500 are up at all. Atmosphere near the horizon dims the faintest of those, and the practical count at any one moment is under a thousand.
So the number describes what the sky holds rather than what the eye collects, and the experience was never a counting exercise. What changes under a truly dark sky is not the tally. It is that the Milky Way stops being a faint smudge and becomes structured, with dark dust lanes running through it, bright enough on the best nights to cast a faint shadow.
What is already being protected here
Badlands National Park was certified an International Dark Sky Park in July 2026, one of roughly 270 certified places on Earth. That certification took the Badlands National Park Conservancy close to a decade of work. The Badlands Astronomy Festival has run since 2012, is free to the public, and is put on with the Black Hills Astronomical Society and the National Park Service.
DarkSky International owns the certification standard, and it took decades to build. This site points at it. It will never issue a rival badge.
Where to read more
- Definition of light pollution, scale of it, and the effects on wildlife: National Park Service, Light Pollution.
- Effects on nocturnal wildlife: NIEHS.
- The five principles, published jointly by DarkSky International and the Illuminating Engineering Society: DarkSky International.
- Badlands certification, July 2026, confirmed against DarkSky International's own announcement and its entry in the Dark Sky Places register.
- The 7,500 figure is the Park Service's, from Enjoy the Night Sky. The naked-eye counts it is compared against are the standard magnitude 6.5 figures, about 9,100 across the whole sky, roughly half of that above any one horizon.