November’s full Moon was called the Beaver Moon by both the colonists and the Algonquin tribes because this was the time to set beaver traps before the swamps froze, to ensure a supply of warm winter furs. It was also called the Full Frost Moon by Native Americans. A full moon is a lunar phase that occurs when the geocentric apparent longitudes of the sun and moon differ by 180 degrees; the moon is then in opposition with the sun. At this time, as seen by viewers on earth, the hemisphere of the moon that is facing the earth (the near side) is fully illuminated by the sun and appears round.