Synodic period

Synodic period is the amount of time it takes for two objects (like the sun and the moon, for example) to line up and appear in the same position in the sky from our point of view. For example, when there is a full moon, the sun and the moon have lined up with each other in the sky. The time it takes for the moon and the sun to line up again and make another full moon is called the synodic period. The synodic period of the moon is about 29.5 days.