Death Valley National Park is a remote place, and in its night sky countless stars, including many in our own Milky Way Galaxy, are visible. But on the park’s eastern horizon, a dome of light appears each night, blotting out stars in that part of the sky. The glow of city lights from Las Vegas creates this “light pollution,” which worldwide now hides the Milky Way from about one-third of humanity, according to a new study in Science Advances.