Artist James Turrell uses the sky as his studio to explore his creative interest in light and space. This fascinating documentary examines Turrell's work, especially his ongoing project at Roden Crater -- a natural cinder volcanic crater near Flagstaff, Ariz., that Turrell is transforming into a giant observatory for beholding celestial phenomena. In interviews, Turrell discusses his research on natural light and his interest in Hopi mythology.