The mean period between successive occurrences of identical lunar phases, e.g. from new Moon to new Moon; also known as a lunation. The synodic month is over two days longer than the Moon’s orbital period (the sidereal month), because of the Earth’s orbital motion around the Sun. The number of synodic months in the year is exactly one fewer than the annual number of revolutions of the Moon around the Earth. The mean length of the synodic month is 29.530 59 days.