The Sturgeon Moon is the traditional name given to the full moon that appears in August. This moniker, like many names for the monthly full moons, is not based on any unique astronomical feature but rather on the seasonal rhythms of life observed centuries ago. The visual experience of this August full moon is governed entirely by atmospheric conditions and human perception, not by the ancient name.
The Moon’s Actual Appearance
Scientifically, the Sturgeon Moon is simply a standard full moon, reflecting the sun’s light when fully illuminated. It does not possess an intrinsic color, size, or brightness that differs from a full moon in any other month.
Any time the Moon appears noticeably larger near the horizon, this is due to the “Moon Illusion.” This psychological effect occurs when the brain compares the low-hanging Moon to terrestrial objects like trees and buildings. This tricks the mind into perceiving it as larger than when it is high in the empty sky.
This coloration is a physical effect caused by Earth’s atmosphere, not unique to the Sturgeon Moon. When moonlight travels through a greater thickness of air as the Moon is low, the atmosphere scatters the shorter, bluer wavelengths of light away. This leaves the longer, redder wavelengths to pass through, creating the warm color. Dust, smoke, or high humidity in the August air can further enhance this reddish appearance.
Why It Is Called the Sturgeon Moon
The name “Sturgeon Moon” originates from the naming traditions of various Native American tribes in North America, particularly those in the Great Lakes region. These groups named the full moons based on seasonal events, harvests, or natural occurrences. The August full moon was named for the large freshwater lake sturgeon that were historically abundant and easily caught in the Great Lakes and Lake Champlain during late summer.
The sturgeon is an ancient species, often referred to as a “living fossil,” and was a reliable food source for Native American communities. The name was popularized when it was included in the Old Farmer’s Almanac, which began publishing the Native American names for full moons in the 1930s. The August full moon also has other cultural names, such as the Green Corn Moon and the Grain Moon, which refer to the ripening of crops.
When to See the August Full Moon
The Sturgeon Moon occurs annually, marking the full moon closest to the end of the summer season in the Northern Hemisphere. A full moon happens roughly every 29.5 days, the length of one complete lunar cycle. Although the Moon is technically only “full” for a moment at peak illumination, it appears completely full to the eye for approximately three days.
For the most striking visual experience, the best time to look for the Sturgeon Moon is shortly after sunset, as it rises above the eastern horizon. Viewing the moon at moonrise allows observers to fully appreciate the dramatic size increase caused by the Moon Illusion. This low position also maximizes the atmospheric reddening effect, making the Moon appear in its deepest orange or red hues. Viewers should check a local moonrise and moonset calculator, as the exact time changes each night.