The Full Harvest Moon is the full moon

Full moon

Full moon lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun.Lunar eclipses can only occur at...

 that occurs closest to the autumnal equinox.

Appearance

All full moons rise around the time of sunset. In general the moon rises about 3 minutes later each day. As it moves in orbit around Earth, the Harvest Moon and Hunter's Moon are special because, around the time of these full moons, the time difference between moonrise on successive evenings is shorter than usual. This means that the moon rises approximately 30 minutes later from one night to the next, as seen from about 40 degrees N. or S. latitude. Thus, there is no long period of darkness between sunset and moonrise around the time following these full moons. In times past this feature of these autumn moons was said to help farmers working to bring in their crops, or in the case of the Hunter's Moon, hunters tracking their prey. They could continue being productive by moonlight even after the sun had set. Hence the name Harvest Moon.

The reason for the shorter-than-usual rising time between successive moonrises around the time of the Harvest- and Hunter's-Moon is that the ecliptic

Ecliptic

The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...

—the plane of Earth's orbit around the sun—makes a narrow angle with respect to the horizon in the evening in autumn.

Times of appearance

The Harvest Moon is the full moon closest to the autumnal equinox. It is the first full moon closest to that equinox. About once every four years, it occurs in October in the northern hemisphere. Currently, the latest possible Harvest Moon is on October 11.

When the night of the Harvest Moon coincides with the night of the equinox, it is called a "Super Harvest Moon". In 2010, the harvest moon happened only 5 1/2 hours after the autumnal equinox, creating the first Super Harvest Moon since 1991.

Often, the Harvest Moon seems to be bigger or brighter or more colorful than other full moons. The warm color of the Moon shortly after it rises is caused by light from the Moon passing through a greater amount of atmospheric particles than when the moon is overhead. The atmosphere scatters the bluish component of moonlight which is really reflected white light from the sun, but allows the reddish component of the light to travel a straighter path to one's eyes. Hence all celestial bodies look reddish when they are low in the sky.

It appears larger in size because the brain perceives a low-hanging moon to be larger than one that's high in the sky. This is known as a Moon illusion

Moon illusion

The Moon illusion is an optical illusion in which the Moon appears larger near the horizon than it does while higher up in the sky. This optical illusion also occurs with the sun and star constellations. It has been known since ancient times, and recorded by numerous different cultures...

, and it can be seen with any full Moon. It can also be seen with constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

s; in other words, a constellation viewed low in the sky will appear bigger than when it is high in the sky.

Other names

The Harvest Moon is also known as the Wine Moon, the Singing Moon, "Blue Corn Moon", and the Elk Call Moon. In myth and folklore

Folklore

Folklore consists of legends, music, oral history, proverbs, jokes, popular beliefs, fairy tales and customs that are the traditions of a culture, subculture, or group. It is also the set of practices through which those expressive genres are shared. The study of folklore is sometimes called...

the full moon of each month is given a name. There are many variations.

In some cultures, individuals whose birthdays fall on or near a harvest moon must provide a feast for the rest of the community.

External links

• Moon Illusion
• Alternate names of the Full Moons.
• Science page from NASA explaining the full moons.
• "Who named the harvest moon?"