Charles Ross’s Spectrum 14 is a calibrated array of prisms that cast a dazzling display of luminous color across the Museum’s rotunda. Bands of spectral lighttraverse the space in relation to the sun, which follows a slightly different arc through the sky every day. Over time, the work changes in response to Earth’s rotational orbit, connecting us to the premodern experience of astronomical observation and calculation that defined cycles of days, seasons, and rituals. This project was commissioned for PST ART as part of the Getty exhibition Lumen: The Art and Science of Light.