Most of us know pollution when we see it. Trash piles up in the street. Air grows so thick with harmful gasses it becomes hard to breathe. Raw sewage runs into a once-clean lake. But people sometimes struggle to recognize another kind of pollution. In fact, this kind of pollution is all about what you can’t see.

Light pollution happens when unnecessary use of light blocks the night sky. Kids who grow up in cities, where countless lights run all night long, might not get to see stars much at all. With all those hot buildings and bright lights, imagine trying to use a telescope there! When city-dwellers get to the country for the first time and see the sky full of stars, they can hardly believe their eyes!

But light pollution doesn’t just affect what people see. It can affect people’s health too. God designed our bodies to wake up in the daylight and sleep at night. People invented electric light. Usually, it serves as a great blessing by making life easier. But too much electric light can confuse the body’s circadian rhythm. The circadian rhythm is a master biological clock. It regulates when we become sleepy and when we're alert. A confused circadian rhythm can make us sick. Life with no night in sight harms animals too. Nocturnal animals are designed to sleep during the day and be awake at night. What can they do when nighttime looks like day?

In 2001, a program called Dark Sky started. Dark Sky teaches people about light pollution. It shows them how to use light well. That means using streetlights, porch lights, and other lights that shine downward instead of all around. That way, light will shine in the spots where people need it instead of toward the night sky.

Dark Sky also sets up International Dark Sky Sanctuaries and Reserves. You can think of these kind of like zoos for stars. Dark Sky makes sure the skies in these places stay dark so that people can enjoy them.

We are “sky stewards.” The sky tells us about God’s glory. What can you do to make sure people can see it?