Understanding Light Pollution
Exploring the impact of artificial light on our night skies and environment
What is Light Pollution?
Light pollution is the excessive or misdirected artificial light that brightens the night sky, reducing our ability to see stars and disrupting ecosystems. Unlike other forms of pollution, light pollution is immediately reversible with proper lighting choices and practices.
Sky Glow
The brightening of the night sky over inhabited areas due to scattered light from streetlights and other sources. This reduces visibility of stars and celestial objects.
Glare
Excessive brightness that causes visual discomfort or difficulty seeing. Common with unshielded lights and can be a safety hazard for drivers and pedestrians.
Light Trespass
Light falling where it is not intended or needed, such as streetlights shining into bedroom windows or neighboring properties.
Light Clutter
Excessive groupings of light sources that create confusion and distraction, commonly seen in over-lit urban areas and commercial districts.
Before & After: The Impact of Light Pollution
Slide to compare the same night sky view with and without light pollution. Notice how many more stars are visible in dark sky conditions.
Lighting Solutions
Different lighting fixtures have varying impacts on light pollution. Explore each option below to learn about best practices for responsible outdoor lighting.
Select a lighting option above to see details
Learn about the features of different lighting options and how they affect light pollution.
Environmental Impact
Select a lighting option above to see its environmental impact.
Cost Analysis
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Global Light Pollution Map
Explore light pollution levels around the world. Click on hotspots to learn more about specific regions and their efforts to combat light pollution.
Location Name
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Bortle Scale: Measuring Sky Darkness
The Bortle scale is a nine-level numeric scale that measures the night sky's brightness. Move the slider to see how different Bortle levels affect star visibility.
Stars Visible: 6000+
Milky Way: Highly detailed with shadows
Excellent
Rural Sky
Bright Suburban
Inner City
Impacts of Light Pollution
Light pollution affects more than just our view of the stars. Explore the various impacts on wildlife, human health, energy consumption, and astronomy.
Wildlife Disruption
Artificial light at night disrupts nocturnal animals, confuses migratory birds, and disorients sea turtle hatchlings. Many species rely on natural darkness for hunting, mating, and navigation.
Human Health
Exposure to artificial light at night suppresses melatonin production, disrupting our circadian rhythm. This has been linked to sleep disorders, depression, obesity, and increased risk of certain cancers.
Energy Waste
Poorly designed lighting wastes energy by directing light where it's not needed. The U.S. alone wastes an estimated $3 billion annually on unnecessary outdoor lighting.
Solutions to Light Pollution
Light pollution is one of the most easily solved environmental problems. Simple changes in lighting design and practices can make a significant difference.
Shield Lights
Use fully-shielded light fixtures that direct light downward where it's needed, not up into the sky. This reduces sky glow and light trespass while improving visibility.
Choose Warm Colors
Use warm-colored lights (under 3000K) instead of cool blue-rich LEDs. Warm lights have less impact on wildlife and human health while reducing sky glow.
Control When Lights Are On
Use timers, motion sensors, and dimming controls to ensure lights are only on when needed and at appropriate brightness levels.
Test Your Knowledge
Take this quiz to see how much you've learned about light pollution and dark sky-friendly lighting.