Every month Earth’s moon goes through its phases, waning and waxing in its constant transformation from new moon to full moon and back again. Full moons occur every 29.5 days or so as the moon moves to the side of Earth directly opposite the sun, reflecting the sun’s rays off its full face and appearing as a brilliant, perfectly circular disk.
For many years, humans have used the movement of the moon to keep track of the passing year and set schedules for hunting, planting, and harvesting. Ancient cultures the world over have given these full moons names based on the behavior of the plants, animals, or weather during that month.
In January amid the cold and deep snows of midwinter, the wolf packs howled hungrily outside Indian villages. Thus, the name for January’s full Moon. Sometimes it was also referred to as the Old Moon, or the Moon After Yule. Some called it the Full Snow Moon, but most tribes applied that name to the next Moon.
• Full Wolf Moon Native Americans and medieval Europeans named January’s full moon after the howling of hungry wolves lamenting the midwinter lack of food. Other names for this month’s full moon include old moon and ice moon.