The ability to synchronize the motion of two oscillating objects has revolutionized technologies, such as clocks, that require precision measurements to operate. For long-distance coupling, researchers typically use electromechanical oscillators, whose motion is driven by electrical actuation and whose synchronization comes from either electronic coupling or a physical connection. Now Chun-Hua Dong of the University of Science and Technology of China and colleagues have demonstrated optical coupling of the motion of a swinging microsphere and of a vibrating microdisk separated by 5 km of optical fiber [1].