The perception of sky is altered through James Turrell's "Tending, (Blue)" at the Nasher Sculpture Center in Dallas. After entering through a nearly hidden, glowing glass door in the museum's garden, visitors curve through a vestibule lighted by shifting red and blue lights to a stone room lined with benches. Through a 9.5-foot-square opening in the ceiling, the sky is visible. But, in this site-specific installation, the familiar blue and the white of clouds is suddenly sharper, more detailed, and closer than ever before.

"Tending, (Blue)" is part of Turrell's "skyspace" series that he started in the 1970s. The American artist created over 25 enclosed spaces that open to the sky, including spaces at P.S.1 in New York, the Israel Museum in Jerusalem, the de Young Museum in San Francisco, the Walker Art Center in Minneapolis, Yorkshire Sculpture Park in England, and the James Turrell Museum in Argentina.

Turrell studied math, psychology, and art history, winding the subjects into works that focus on and redefine the environment through sculpture. His largest project is Roden Crater in Arizona, where he has spent over 30 years moving more than 1,350,000 cubic yards of rock to transform the volcanic site into a "secular cathedral" of chambers, passageways, and viewing spaces where people can observe celestial occurrences.

The square framing the sky in "Tending, (Blue)" has an edge as thin as a knife, eliminating the appearance of roof thickness and giving the illusion of the sky being stretched close over the space. A complicated coordination of colored lights plays against the changing atmospheric conditions in downtown Dallas, as well as the cycle of the sun and the seasons. Sunrise and sunset are particularly entrancing, when the colors of the sky and interior lights are most dynamic, softly evolving at sunrise and then rapidly moving to seemingly impossible colors at sunset.

Occasionally, the museum even has late night events where the skyspace is open to the stars.