James Turrell is an American artist known for his light installations. Some of his most notable works include projection pieces from the 1960s that use colored lights and skyspaces, outdoor installations creating the illusion of sky and light through architectural features. His largest ongoing project is Roden Crater, a natural crater he is transforming into a massive naked-eye observatory through tunnels, alcoves and light. Turrell's works aim to manipulate viewer perception of light, space and time through minimal use of technology.