Dark Night Sky: A natural lightscape, such as a dark night sky, is an environment that has not been disturbed by light or air pollution. In Yosemite, dark night skies have natural, cultural, and scenic importance. Animals, especially nocturnal ones, depend on darkness to hunt, conceal their location, navigate, and reproduce. Plants can be affected by artificial light because it disrupts their natural cycles. Many Yosemite visitors come to experience this worldwide vanishing resource. To study the topic, the National Park Service devised a system to measure sky brightness, and even remote parks like Yosemite face stray light pollution, particularly from the San Joaquin Valley.