Spring Equinox

Spring Equinox (Chunfen), also known as “Ascending Equinox” (Sheng Fen), and anciently called “Mid-day” (Rizhong), “Day-Night Equal” (Riye Fen), or “Mid-Spring Month” (Zhongchun Zhi Yue), is the fourth of the twenty-four solar terms. It occurs when the Big Dipper points to the terrestrial branch mao and the sun reaches the ecliptic longitude of 0°, typically falling on March 19–22 in the Gregorian calendar.

The term “fen” in Chunfen has two meanings. One is the “equal division of the season”: traditionally, the period between Lichun (Beginning of Spring) and Lixia (Beginning of Summer) constitutes spring, and the Spring Equinox falls exactly midway between these two solar terms, thus dividing the season equally. The other meaning is the “equal division of day and night”: on the day of the Spring Equinox, the sun shines directly over the equator, and day and night are of equal length, each lasting 12 hours. This holds great significance in astronomy, for after this day the direct point of the sun's rays continues to move northward from the equator into the Northern Hemisphere, causing daylight to gradually exceed nighttime in the Northern Hemisphere — and the opposite in the Southern Hemisphere. Climatically, distinctive features also emerge: warm weather, bright sunshine, and ample rainfall. After Chunfen, with the exception of the Qinghai-Tibet Plateau, the northeastern regions, the northwestern regions, and the northern parts of North China, almost all of China enters a radiant spring, and the overwintering crops in most regions enter their spring growth phase.

Chunfen is a solar term of the Chinese lunar calendar. As far back as the Spring and Autumn period, the Mid-Spring season was already identified, and by the Qin and Han dynasties, the complete system of the twenty-four solar terms was fully established. The earliest records of the term Chunfen can be traced back to the Rites of Zhou (Zhou Li), with further descriptions appearing in ancient texts such as the Book of Documents (Shang Shu) and the Classic of Poetry (Shi Jing).

Chunfen holds important significance in astronomy — on this day, day and night are of equal length in both the Southern and Northern Hemispheres. It also exerts a profound influence on agricultural production, as after Chunfen the peak sowing season officially arrives, various crops begin to grow, and both flora and fauna come back to life. The Spring Equinox is also associated with folk activities such as spring outings and spring sacrificial rites; customs include flying kites, eating spring vegetables, and the game of egg-standing.