fl. c. 350 B.C.

Babylonian astronomer who may have developed the 19-year Babylonian calendar, and who was among the first to recognize the irregular velocity of the Sun and planets. Director of the astronomical school at Sippar, Kiddinu probably created the system by which the Babylonians aligned their lunar and solar calendars by including intercalated months at assigned intervals over a 19-year-period. He also developed what later came to be called System B, the Babylonian method of describing the irregular velocities of heavenly bodies. In addition, Kiddinu calculated the length of the synodic month at 29.530614 days, almost exactly the correct value.