The solar term of Qiu Fen (Autumn Equinox)

Qiu Fen, the sixteenth solar term in the twenty-four solar terms, is the fourth solar term in autumn. It signifies the sun’s celestial longitude reaching 180 degrees, falling around September 22-24 in the Gregorian calendar. On the day of Qiu Fen, the sun is almost directly above the Earth’s equator, resulting in equal day and night lengths worldwide. Qiu Fen, where ’fen’ means ’divide’ or ’half,’ not only indicates the equal division of day and night but also symbolizes the division of the autumn season. After Qiu Fen, the direct sunlight shifts southward, leading to shorter days and longer nights in the Northern Hemisphere, with an increasing temperature difference between day and night as temperatures gradually drop.