A full moon occurs when the moon, the Earth and the sun are lined up, with the Earth in between the sun and the moon. This allows us to see the entire disc of the moon illuminated in reflected sunlight. While 2016 will have 12 full moons, some years have 13 because the full moon phase occurs every 29.53 days.
Native Americans attributed certain terms to each month’s full moon based on seasonal factors. Naming the moons helped them keep track of the seasons; the moons were a part of their calendar, particularly important in regulating farming and hunting activities.