That’s not a UFO on the roof of the Art Institute of Chicago. Lunar, a solar-powered, spacecraft-looking sculpture by artist Spencer Finch, is shaped like a "buckyball"—named for the geodesic dome invented by the architect Buckminster Fuller–-and glows with the light of a full moon over Chicago. Finch measured the amount of moonlight in the city during the summer using a colorimeter, a device that measures the average color and temperature of light in a specific place and time. The luminosity is reconstructed using LED lights that have a bluer quality and filtered through the orange polycarbonate of the buckyball. The aluminum structure contains solar panels that collect sunlight during the day that it converts to moonlight over the darkened autumn and winter months.
Finch has done this sort of thing before. His 2003 work Moonlight replicated the light of a desert full moon that shone over a county in New Mexico one July evening. But the preparations for a Chicago winter had unexpected challenges. "The hardest part was getting the piece designed so that it wouldn’t blow off the roof," the artist tells Co.Design. So in the end, each foot of the sculpture was filled with lead and ended up weighing 2,500 pounds.