The Autumnal Equinox, known as "秋分" (Qiū Fēn) in Chinese, is one of the 24 solar terms in the traditional Chinese calendar. It typically falls around September 22nd or 23rd in the Northern Hemisphere. During this time, the day and night are approximately of equal length, marking the transition from summer to autumn.

The Autumnal Equinox carries significant cultural and agricultural importance in Chinese tradition. It symbolizes the time when the daylight hours begin to decrease, temperatures start to cool, and nature prepares for the harvest season. It is a time for people to appreciate the bountiful harvests, express gratitude for the earth's blessings, and celebrate the changing of seasons.