What is Light Pollution?

The 24-hour diel cycle is characterized by the presence of light, which comes from various sources. During the day, the world is brightly illuminated by the sun, which is contrasted to the period of night, considered ‘dark’ in comparison. However, the night is full of light if you know where to look - from the phases of the moon, to the brilliance of the stars above and the arching Milky Way galaxy, to zodiacal light and the Aurora Borealis. Any additional source of artificially produced light is considered as light pollution, as this stimulant exceeds light levels produced by naturally occurring sources.

However, humans use artificial light for a myriad of reasons - from enhancing human safety in areas of concern, such as entryways, staircases, sidewalks, and roads; lighting fires for recreational and commercial purposes, such as oil rigs; to entertainment after the sun sets; the list goes on. Clearly, we use artificial light as a resource, so how can we identify when artificial light is a pollutant that needs to be addressed? Can we coexist with natural darkness and enjoy the night for all of its splendor? 

Why does it matter?

Light pollution impacts nearly every aspect of our lives, including our health, safety, and environmental justice. Humans have an innate connection with the night sky, spanning across generations, as societies relied on the seasonal patterns of constellations to pass down stories and important lessons. The Milky Way’s majestic presence also gives us an intimate introspective into the human experience. Beyond that, light also impacts the natural environment and disrupts entire community assemblages. Wasting light means wasting energy and financial resources that could be used for other projects. Below are just some examples of light pollution’s impacts, but a high-level overview is provided in DarkSky International’s 2023 State of the Science Report

All of these facets can be immediately improved by reducing wasteful and unnecessary light.

How to identify when artificial light is an issue

The easiest indicator is whether a light is obtrusive or excessive. If misused, artificial lights can actually reduce our visibility of the surrounding environment, making it less safe. If the light serves no clear purpose or task, it is wasteful and therefore polluting the nighttime environment. There are four main types of light pollution.

Did you know the domes of light produced by cities in Miami-Dade, Broward, Palm Beach, and Collier Counties are visible from Big Cypress National Preserve, a certified International Dark Sky Park? Even this protected place is not safe from encroaching light pollution.

Solutions to light pollution 💡

The solution to light pollution is as easy as turning off lights we don’t need - that’s it! 

The National Audubon Society and chapters like the Tropical Audubon Society promote this every year with its Lights Out campaigns to encourage homeowners, businesses, and municipalities to turn off unnecessary lights during peak bird migration. 

If we can live without these lights for a few nights of the year, why not take it a step further and turn off unnecessary lights every night?

Because there are reasons to keep certain lights on at night, DarkSky International partnered with the Illuminating Engineering Society to promote the Five Principles for Responsible Outdoor Lighting

How you can employ these principles with the lights you interact with? The graphic below illustrates how these principles lead to reduced light pollution and a visible night sky to enjoy.

Remember: the ‘best’ solution employs all five principles - fully shielded to direct the light on the targeted surface where it is needed; reducing the timing and duration of light to when it is needed; using warmer color of the light; and the least amount of light intensity needed, no more and no less for the intended task. 

How do quality lights look in action? Here are a few examples of quality outdoor lighting taken by night sky advocates in other regions:

Dark Skies Initiative, McDonald Observatory

City of Tucson retrofit project, DarkSky International

Objective Starry Sky, Mont-Megantic Dark Sky Reserve

Let's work together to promote responsible outdoor lighting in our communities - to save money and energy, and to protect people, wildlife, and ecosystems across the Greater Everglades!