How often do we have a Full Moon?
The phases of the lunar cycle are dictated by a number of factors, including the Moon’s orbit around Earth and, by extension, the Sun.
A Full Moon only occurs when the lunar orb sits directly across from the Sun, with our home planet in between the two.
The Sun’s rays can then fully illuminate the one side of the Moon we always see from Earth.
This is important because every time you look at the Moon, you are always looking at the same side of the satellite.
Another factor is the length of the lunar cycle or lunar month – about 29.53 days.
source: express.co.uk