Diane Knutson is a former National Park Ranger and the creator of the Lights Out Movement in Rapid City, South Dakota. Light pollution not only impacts our view of the universe, but our environment, our individual health, and energy consumption. Not long ago, the starry night sky was clearly visible -- now, songbirds mistake city skylines for the rising sun, eight out of ten children will never see the Milky Way, and exposure to artificial light at night has been linked to physical and mental health problems. Knutson explains the problem with light pollution and provides solutions for regaining a dark sky.