Scientists Say: Light pollution

This is when artificial light leaks into places that are normally dark


People produce so much extra light that our light pollution can be seen from space.

Craig Mayhew and Robert Simmon/NASA GSFC

Light pollution (noun, “LIE-T Poll-OO-shun”)

This is when light from non-natural sources shines in places that are naturally dark. This artificial light is any kind of light made by people. Streetlights illuminating an area at night produce light pollution. So do the lights from buildings, cars and even campfires.

Lights at night can provide safety for people — think of how difficult or dangerous it would be to walk down a city street or through a parking lot in the dark. But this light is not so great for other organisms. It can mess with the circadian rhythms of plants and animals. And biological functions that occur in 24-hour cycles, such as when insects come out and pollinate night-blooming plants and when plants grow or bloom, can also be disrupted by this light. It can also lead migrating birds astray and force seabirds to land, exposing them to predators.

Light pollution can make it especially hard for people in cities and towns to see stars and planets. That’s why it’s often easier to stargaze in the country than in the city. 

In a sentence

People are so sensitive to light pollution that even a full moon will disrupt our shut-eye.

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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