The full moon that occurs in May is commonly known across the northern hemisphere as the Flower Moon. This name is part of a tradition where each full moon of the year is given a specific designation, often reflecting a seasonal occurrence in nature or a change in agricultural activity. The use of these descriptive names connects the celestial calendar with the rhythms of the terrestrial world, serving as a practical way to track the passage of time before the adoption of modern calendars.
The May Full Moon Defined
The Flower Moon is not a separate or unique astronomical phenomenon, but rather the designation for the full moon phase that takes place during the calendar month of May. A full moon occurs roughly once every 29.5 days, which is the duration of a synodic month. Since May contains 31 days, it is nearly guaranteed to host a full moon each year. The moment of the full phase is when the Moon is perfectly opposite the Sun, causing its entire face to be illuminated from our perspective.
This recurring alignment is a common feature of lunar calendars, which historically linked the cycle of the Moon’s phases to the annual cycle of the seasons. The name “Flower Moon” serves as a temporal marker, identifying a specific full moon within the 12 or 13 that occur each year. The Moon itself does not appear different from any other full moon.
Why It Is Called the Flower Moon
The name is directly tied to the abundance of flora that blooms across much of North America during late spring. This period in May marks a significant transition from the early growth of April to the full greenery of summer. The widespread blossoming of flowers gave rise to the name, reflecting the most noticeable seasonal event of the month.
The tradition of seasonal naming is widely attributed to various Native American tribes, particularly the Algonquin peoples of eastern Canada and the northeastern United States. They used the lunar cycle as a practical calendar to track the seasons and plan their activities. The Flower Moon name was adopted by Colonial Americans and subsequently entered popular culture as the standard designation for the May full moon.
The name highlights a time of significant natural renewal. This blossoming period signaled warmer weather and the availability of plant-based resources, making the Flower Moon a meaningful marker for those who depended on the natural world.
Names Used by Other Cultures
While the Flower Moon is the most recognized name, the May full moon was known by a variety of other names across different Native American tribes and European cultures, each reflecting local seasonal activities. Many of these alternative names center on agriculture and animal behavior. For instance, the Dakota and Lakota tribes often referred to it as the Planting Moon, marking the traditional time for sowing seeds into the ground.
The Cree people used names such as the Budding Moon or Leaf Budding Moon, which emphasized the vigorous growth of leaves and new plant life. They also referred to it as the Frog Moon or Egg Laying Moon, drawing attention to the animals that become active in the warming season. In European traditions, it was sometimes called the Milk Moon, referencing the increased milk production of livestock during the lush pastures of spring.