The Next Full Moon is a Partial Lunar Eclipse; a Supermoon; the Corn Moon; and the Harvest Moon

The full Moon will be tonight, September 17, 2024, at 10:35 PM EDT. This will be on Wednesday from Newfoundland and Greenland Time eastward across Eurasia, Africa, and Australia to the International Date Line. Most commercial calendars will show this full Moon on Wednesday based on Greenwich or Universal Time. The Moon will appear full for about three days, from Monday evening through Thursday morning.

This will be a partial lunar eclipse. The Moon will start entering the Earth's partial shadow at 8:41 PM EDT. The slight dimming of the Moon will be difficult to notice until the top edge of the Moon starts entering the full shadow at 10:13 PM. The peak of the eclipse will be at 10:44 PM with only the top 8 percent of the Moon in full shadow. The Moon will finish exiting the full shadow at 11:16 PM and the partial shadow on Wednesday morning at 12:47 AM.

The main phases of the Moon are illustrated in a horizontal row, with the new moon on September 2nd, first quarter on September 11th, full moon on September 17th, and the third quarter moon on September 24th.

This will be a supermoon. The term "supermoon" was coined by astrologer Richard Nolle in 1979 as either a new or full Moon that occurs when the Moon is within 90% of its closest to Earth. Since we can't see new Moons, what has the public's attention are full supermoons, the biggest and brightest Moons of the year. Although different publications use different thresholds for deciding which full Moons qualify, most agree this will be the second of four consecutive supermoons (effectively tied with the full Moon in October for the closest of the year).

The Maine Farmer's Almanac first published "Native American" names for the full Moons in the 1930s and these names have become widely known and used. According to this almanac, as the full Moon in September in the northeastern USA called this the Corn Moon, and in Mohawk 'Iethi'sotha Ahsonthenhkwa Karahkwa' as this was the time for gathering their main staple crops of corn, pumpkins, squash, and beans.

As the full Moon closest to the autumnal equinox, this is the Harvest Moon. The first known written use of this name in the English language (per the Oxford English Dictionary) was in 1706. During the fall harvest season farmers sometimes need to work late into the night by moonlight. On average moonrise is about 50 minutes later each night. Around the Harvest Moon this time is shorter, about 25 minutes for the latitude of Washington, DC, and only 10 to 20 minutes farther north in Canada and Europe.

Other European names for this full Moon are the Fruit Moon, as a number of fruits ripen as the end of summer approaches, and the Barley Moon, from the harvesting and threshing of barley.

For Hindus, this full Moon marks the end of Ganesh Chaturthi and the start of Pitru Paksha. Ganesh Chaturthi (also called Vinayaka Chaturthi or Vinayaka Chavithi) is a 10 or 11 day festival honoring the god Ganesha that ends with this full Moon. Ganesha is easily recognized by his elephant head and is worshiped as the god of beginnings, wisdom, arts and sciences, and as the remover of obstacles. Throughout the festival celebrants offer food, sweets, and prayers to clay statues of Ganesha at home and on public stages. Traditions include chanting of Vedic hymns and Hindu texts, prayers, and fasting. On the last day (near the full Moon), people carry the statues to a nearby river or ocean and immerse them. As the clay dissolves, Ganesha is believed to return to his parents, the god Shiva and goddess Parvati, on Mount Kailash.

Pitru Paksha (fortnight of the ancestors) is a 15 days long festival that ends with the new Moon. During this time, Hindus honor their ancestors (pitrs) with rituals, food offerings, and scripture reading. Pitru Paksha is also known by a number of other names.

For some Buddhists in Bangladesh and Thailand this full Moon is Madhu Purnima, the Honey Full Moon Festival or the Honey-offering Festival. The legend is that when the Buddha was trying to bring peace between two factions in a forest, an elephant and a monkey fed him, with the elephant offering fruit and the monkey offering a honeycomb.

In China, Vietnam, and some other Asian countries, this full Moon corresponds with the Mid-Autumn Festival, a traditional harvest festival. In China, other names for this festival include the Moon Festival, the Mooncake Festival, and the Reunion Festival (with wives visiting their parents then returning to celebrate with their husbands and his parents). Part of the festival includes offerings to the Moon Goddess Chang'e (the name the China National Space Agency gives their lunar missions).

In Korea, this full Moon corresponds with the harvest festival Chuseok, during which Koreans return to their traditional hometowns to pay respect to the spirits of their ancestors.

This full Moon corresponds with the first of two Japanese Tsukimi or "Moon-Viewing" festivals, also called Imomeigetsu (which translates as "potato harvest Moon") because of the tradition of offering sweet potatoes to the Moon. These festivities have become so popular that they are often extended for several days after the full Moon.

In many traditional Moon-based calendars the full Moons fall on or near the middle of each month. This full Moon is near the middle of the eighth month of the Chinese year of the Dragon and Rabi' al-Awwal in the Islamic calendar, the month in which many Muslims celebrate Mawlid, the birth of the Prophet Muhammad. This full Moon is near the middle of Elul in the Hebrew calendar. Elul is a time of preparation for the High Holy Days of Rosh Hashanah and Yom Kippur. Customs include granting and asking others for forgiveness as well as beginning or ending all letters with the wish that the recipient will have a good year.

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Go out and observe the Moon, participate in a moon lodge ceremony (women only!). Fully enjoy this harvest season (including corn, fruit, and sweet potatoes, and honey), remember your ancestors, stay in touch with your parents, and forgive and ask forgiveness.

With contributions by Gordon Johnston, NASA.