We Mainers are proud, and protective, of our coastline and forests, our clear waters and crisp air. They're a big part of what separates us from the other guys.

But we don't often think of our night sky that way. And we probably should.

Most Mainers can look up on a clear night and see a dark sky full of stars, including the band of stars and light at the edge of our own galaxy. Most other Americans can't see the Milky Way from where they live. Some can see only a few bright stars.

"It distinguishes us from more polluted areas. Just like cleaner waters, darker skies are an attribute," said Robert Burgess, a bank executive from Brunswick by day and amateur stargazer by night.

Light pollution # artificial light that is reflected or shined upward # creates a glow over cities and washes out the night sky in most of the U.S. and other developed countries. It's drawing increasing attention worldwide as a problem, and not just for astronomers.

The absence of darkness and stars can interfere with the behavior of all kinds of animals, from birds to sea turtles. And recent research has linked nighttime brightness to higher rates of breast cancer in women, suggesting that humans need darkness, too.

Maine is relatively unpolluted, light-wise. In nighttime satellite images, the Down East coast and North Woods stand out as the largest, darkest spots in the United States east of the Mississippi River.

This week, the state unveiled some new technology that could help keep it that way.