In 1931 Calder created his first kinetic objects, or mobiles, moved by electric motors. He soon realized that his sculptures could move by themselves. Responding to air currents, Yellow Moon shifts spontaneously. As Calder once said, “a mobile is a piece of poetry that dances with the joy of life and surprise.” Crafted entirely by the artist’s hand Yellow Moon evokes outer space, with stars and orbiting planets: the yellow moon counterbalances the red circle, possibly symbolizing the heat-emanating sun. This may be inspired by a moving vision of a bright sunrise and a vanishing full moon, on opposite horizons, that Calder witnessed as a merchant marine off Guatemala in 1922.