The moon's lunar cycle is close to how many days long?

27 1/2 days to occur and 29 1/2 days to see. is this true? and how does that work? No, that's not quite it. You see the phases as they occur, and that process takes 29+ days. It is the sidereal period of the moon, the true 360 degree orbit around earth, that takes 27+ days. This is very counter-intuitive and you need to understand the difference between synodic and sidereal cycles to understand the difference. Once you understand this difference it will be very clear.