Microsoft Logo Clarity Methow Dark Sky Coalition Install manually Installation methods Installed your code? It can take up to 2 hours to start seeing data. Learn more Clarity masks all sensitive content on your site by default Learn more Copy and paste the Clarity code into the element of your site or app.
top of page

Light Pollution

Information via

Less than 100 years ago, everyone could look up and see a spectacular starry night sky. Now, millions of children across the globe will never experience the Milky Way where they live. The increased and widespread use of artificial light at night is not only impairing our view of the universe, it is adversely affecting our environment, our safety, our energy consumption/climate and our health.

What is Light Pollution?

Most of us are familiar with air, water, and land pollution, but did you know that light can also be a pollutant?


The inappropriate or excessive use of artificial light – known as light pollution – can have serious environmental consequences for humans, wildlife, and our climate. Components of light pollution include:

  • Glare – excessive brightness that causes visual discomfort

  • Skyglow – brightening of the night sky over inhabited areas

  • Light trespass – light falling where it is not intended or needed

  • Clutter – bright, confusing and excessive groupings of light sources

Light pollution is a side effect of industrial civilization. Its sources include

building exterior and interior lighting, advertising, commercial properties,

offices, factories, streetlights, and illuminated sporting venues.


Much outdoor lighting used at night is inefficient, overly bright, poorly targeted,

improperly shielded and, sometimes, completely unnecessary. This light, and

the electricity used to create it, is wasted by spilling it into the sky, rather than

focusing it on to the actual objects and areas that people want illuminated.

Glossary of Lighting Terms

How Bad is Light Pollution?

With much of the Earth’s population living under light-polluted skies, "over-lighting" is an international concern. If you live in an urban or suburban area, all you have to do to see this type of pollution is go outside at night and look up at the sky.

According to the 2016 groundbreaking World Atlas of Artificial Night Sky Brightness,” 80% of the world’s population lives under skyglow. In the US and Europe, 99% of the public can’t experience a natural night.

If you want to find out how bad light pollution is where you live, use this interactive atlas of artificial sky brightness created from the ”World Atlas” data or the NASA Blue Marble Navigator for a bird’s eye view of the lights in your town.  And don’t forget to check out the Globe at Night interactive light pollution map data created with eight years of data collected by citizen scientists.

Effects of Light Pollution

For three billion years, life on Earth existed in a rhythm of light and dark that was created solely by the illumination of the Sun, Moon and stars. Now, artificial lights overpower the darkness and our cities glow at night, disrupting the natural day-night pattern and shifting the delicate balance of our environment. The negative effects of the loss of this inspirational natural resource might seem intangible. But a growing body of evidence links the brightening night sky directly to measurable negative impacts including


Light pollution affects every citizen. Fortunately, concern about light pollution is rising dramatically. A growing number of scientists, homeowners, environmental groups and civic leaders are taking action to restore the natural night. Each of us can implement practical solutions to combat light pollution locally, nationally and internationally.

You Can Help!

The good news is that light pollution, unlike many other forms of pollution, is reversible and each one of us can make a difference! Just being aware that light pollution is a problem is not enough; the need is for action. You can start by minimizing the light from your own home at night by following these simple steps:

  • Learn more. Check out's Light Pollution blog posts

  • Only use lighting when and where it’s needed

  • If safety is concern, install motion detector lights and timers

  • Properly shield all outdoor lights

  • Keep your blinds drawn to keep light inside

  • Become a citizen scientist and help measure light pollution


Learn more about Outdoor Lighting Basics

Spread the word to your family and friends and tell them to pass it on. Many people either don’t know or don’t understand a lot about light pollution and the negative impacts of artificial light at night. By being an ambassador and explaining the issues to others, you will help bring awareness to this growing problem and inspire more people to take the necessary steps to protect our natural night sky.


Dark Sky International has many valuable resources to help you, including Public Outreach MaterialsHow to Talk to Your NeighborLighting Ordinances and Residential and Business Lighting.


Want to do more? Contact Us

The infographic illustrates the different components of light pollution and what “good” lighting looks like. Image: Anezka Gocova, in “The Night Issue”

Alternatives Journal 39:5 (2013).


Before and during the 2003 Northeast blackout, a massive power outage that affected 55 million people. Photo by of Todd Carlson


NASA Blue Marble Navigator

Globe at Night Light Pollution Map


Atlas of Artificial Sky Brightness

bottom of page