Autumn Equinox

Meaning

The Autumn Equinox, Qiufen, is the sixteenth of the twenty-four solar terms: the Sun at 180°, about 23 September, crossing the celestial equator southward. Day and night are again of nearly equal length everywhere, and from now on the nights of the northern hemisphere are longer than the days.

Its name says “autumn divided”: as with the spring equinox, the Chinese year sets it in the middle of its season, halfway between Liqiu and Lidong. It is a principal term, the middle of the Rooster month, and it names the eighth lunar month, the month of the Mid-Autumn Festival, whose full moon usually falls within a fortnight of it.

Its three pentads turn the spring ones round: the thunder withdraws its voice, the creatures that will sleep through winter begin to seal their burrows, and the waters begin to dry. The balance of the day is read again as a balance of yin and yang, but now the dark is gaining on the light.

In practice

• In BaZi nothing turns at the equinox: the month pillar stays the Rooster month’s until Hanlu. A birth near it is no nearer a change of pillar.
• In the Chinese calendar it names the eighth lunar month.
• The Calendar marks it on its day, with the Sun at 0° Libra, as the middle of the Rooster month; astrology marks the same instant as the Sun’s entry into Libra.
• In the zodiac and Feng Shui the month animal and the month’s star are those of the Rooster month, from Bailu to Hanlu.

Across traditions

• In Western astrology the Sun enters Libra, the scales, at this very moment: the sign’s own image is the balance of day and night.
• In Japan Shūbun no hi is a national holiday, in the middle of the autumn week of Higan, when families visit their ancestors’ graves; in Korea it is chubun, and Chuseok, the harvest festival of the eighth lunar month, often falls near it; in Vietnam it is thu phân.
• Across Europe harvest festivals and Michaelmas, on 29 September, gather in the same weeks the thanks for the year’s crops.

Origin and history

The autumn equinox is as old as its spring twin in Chinese astronomy: the Canon of Yao, in the Book of Documents, sets mid-autumn by the night of equal length and a star at dusk, and the gnomon’s noon shadow gave the court its day. The “Twelve Months” of the Lüshi Chunqiu gives its signs, and the Huainanzi its place among the twenty-four.

The moon has long belonged to this term. Under the Ming and the Qing the emperor offered a sacrifice to the Moon at the Altar of the Moon, west of Beijing, on the autumn equinox, as he did to the Sun at the spring one; the popular Mid-Autumn Festival, on the fifteenth day of the eighth lunar month, grew beside it. Since 2018 China has also kept the day of Qiufen as its Farmers’ Harvest Festival.

How Ulune calculates it

Ulune takes the Autumn Equinox as the instant the Sun’s apparent longitude reaches 180°, from its table of the solar terms computed with the Swiss Ephemeris for 1800 to 2200. As a principal term it changes no pillar; the Calendar shows it on the reader’s own date. In 2026 it fell on 23 September at 00:05 UT.

Correspondences