James Turrell works with the medium of light like no other artist of the time. Since the sixties, he has been building spaces which allow light - mostly colored - to be experienced in its material and, at the same time, spiritual qualities. Recently, Turrell has been increasingly interested in the staging of architecture using light. With his light installation for the opening of the Kunsthaus Bregenz, his light design for an administrative building at Leipzig and the light events on the time-honoured Pont du Gard, he established a new group of works. His all-inclusive light staging of Planet m, featured in this book with numerous photographs, sketches, interviews, comparative illustrations and an essay, can only be called spectacular. The pavilion of the media enterprise Bertelsmann, the secret landmark of the EXPO at Hanover, takes on a second, nightly life through Turrell´s ever-changing atmospheres of light. Light, in its encounter with architecture, may be experienced as a pure medium, only to provide expressive architecture with the aura that reveals it as an immaterial sign - as a planet of mediality.