Even in the vastness of the American West, the glow from cities has become so bright that places with truly dark skies at night are becoming an endangered species. In the continental US, experts predict that in a decade, there will be just three areas where the sky will be dark enough to see the Milky Way clearly, the Arizona Republic reports. One area covers part of eastern Oregon and western Idaho, another includes parts of Nevada and western Utah, a third takes in parts of northern Arizona and southern Utah—and the latter two are in danger from the bright lights of Las Vegas and Phoenix, which can be seen for more than 200 miles.
Light pollution not only hinders astronomy, it can disrupt ecosystems and people's sleeping patterns, warns the International Dark-Sky Association. The Tucson-based organization has been trying for years to preserve the West's dark spots, encouraging cities to adopt dark-sky-friendly lighting codes. This month, the group launched a campaign to preserve and promote the dark skies over the Colorado Plateau, stressing its value as a "celestial treasure and a celestial refuge" that has attracted visitors for centuries. "People need the sense of beauty and perspective and awe that we get from our exposure to the universe in a dark night sky," Grand Canyon ranger Marker Marshall tells the Republic. "It's part of every culture, part of being human—to contemplate what's above us." (Click to read about how the full moon messes with your sleep.)