THE blue color of the sky on a clear day is familiar to all. And yet how many have considered the source of this delicate mantle of azure which Nature spreads over the dome of the heavens?

Even if you don't see the rainbow of colors lighting up the night ... The roughly 150 Dark Sky Places in the U.S. fall into five International Dark Sky categories: parks, sanctuaries, reserves ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to ...