On Tuesday May 8, at 7 p.m., bidders will have a rare chance at acquiring one of Alexander Calder’s mobiles. Christies will auction off one red and one white mobile that architect Eliot Noyes commissioned from Calder for his home in New Canaan, Conn., where he had set up his practice in the 1940s. The house had a central courtyard that allowed the mobiles to be seen from all sides of the glass-walled building. Noyes was a member of the Harvard Five, along with Philip Johnson and Marcel Breuer. He was also the first director of the new Industrial Design department at the Museum of Modern Art, where he met Calder in 1941 when the sculpture artist was installing one of his first exhibitions. The two became friends, leading to the collaboration that produced the painted-sheet-metal-and-wire mobiles—one executed in 1950, and one in 1957—that then hung in Noyes’s home for over 50 years. Christies estimates their value at $3.5 million to $4.5 million each. • christies.com