How long does a complete lunar cycle take?

The duration of a complete lunar cycle, which is also known as a synodic month, is approximately 29.5 days. This cycle is defined as the time it takes for the Moon to return to the same phase (for example, from one full moon to the next full moon). The reason it takes about 29.5 days rather than a neat 28 or 30 days has to do with the Moon's orbit around the Earth and the Earth’s movement around the Sun. As the Earth travels in its orbit, the position of the Moon relative to both the Earth and the Sun changes, necessitating a slightly longer period for the Moon to complete its phases. This is why 29.5 days is the most accurate representation of a lunar cycle.