What Moon is That?

"Don't go around tonight,
Well, it's bound to take your life,
There's a bad moon on the rise."
-Bad Moon Rising by Creedance Clearwater Revival

I've always loved Astronomy so one of my daily stops for great images and a daily dose of science is Astronomy Picture of the Day. Occasionally they'll have a picture of a full moon and describe it as the Hunter's Moon or the Wolf Moon. Huh? Who made up these names?

Throughout history civilizations have marked time according to the moon. The Algonquian confederation of Indians (from New England to the Great Lakes) used these names to track the seasons:

Jan. Wolf Moon

Feb. Snow Moon

Mar. Worm Moon

Apr. Pink Moon

May Flower Moon

June Strawberry Moon

July Buck Moon

Aug. Sturgeon Moon

Sep. Harvest Moon

Oct. Hunter's Moon

Nov. Beaver Moon

Dec. Cold Moon

Early settlers of New England like the idea of giving names to the Full Moon so they adopted the custom with some changes:

Jan:  Old or Ice Moon
Feb:  Wolf, Hunger, Storm, Candles Moon
March: Lenten, Crow, Crust, Sugar, Sap, Chaste, Death Moon
April:  Egg (Easter), Fish, Seed, Waking Moon
May: Milk, Corn Planting, Corn, Hare Moon
June: Flower, Honey, Rose, Hot, Planting Moon
July: Hay, Thunder, Mead Moon
Aug Grain, Red, Green Corn, Lightning, Dog Moon
Sept: Fruit, Corn, Barley Moon
Oct: Harvest, Travel, Dying Grass, Blood Moon
Nov: Hunter's, Frost, Snow Moon
Dec: Oak, Frost, Winter, Yule Moon

It's not so obvious from the list but some moons got changed from one month to the next like Hunter's from Oct to Nov. The lunar orbit of 28 days makes the full moon shift on the calendar and drift relative to the equinox's (start of spring, summer, fall, winter).

Bottom Line

There are 12.37 full moon in a year so one out of every three years will have 13 full moons. The extra moon is called the Blue moon? It was mistakenly thought from an error in the 1946 Sky & Telescope that the second month in the same month was "Blue". But the correct definition is that when a "season" (fall: Oct-Dec, winter:Jan-March, etc) has four moons, the 3rd moon is Blue. Horrible definition but it must have made sense to someone who made it up.