Spring Equinox

Meaning

The Spring Equinox, Chunfen, is the fourth of the twenty-four solar terms: the Sun at 0° of its path, about 21 March, crossing the celestial equator northward. Day and night are of nearly equal length everywhere on Earth, and from now on the days of the northern hemisphere are longer than its nights.

Its name says “spring divided”: in the Chinese year the equinox is not the start of spring but its middle, halfway between Lichun and Lixia. It is a principal term, the middle of the Rabbit month, and it names the second lunar month.

Its three pentads are the swallows coming back, the thunder making its voice heard, and the first lightning. The balance of the day is read as a balance of yin and yang, the light now gaining on the dark. From now on the Sun stays north of the equator for half a year, and the warm half of the northern year begins.

In practice

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

Across traditions

• In Western astrology the equinox is the start of the zodiac itself: the Sun enters Aries, and the tropical year is counted from this point.
• In Iran and Central Asia Nowruz, the new year, begins at the equinox; Easter is reckoned from it, the first Sunday after the first full moon on or after 21 March.
• In Japan Shunbun no hi is a national holiday, in the middle of a week of Higan when families visit their ancestors’ graves; in Korea it is chunbun, in Vietnam xuân phân.

Origin and history

The equinoxes are among the oldest dates of Chinese astronomy. The Canon of Yao, in the Book of Documents, sets mid-spring by the day of equal length and a star at dusk, and the gnomon’s noon shadow, halfway between its longest and its shortest, fixed the day for the court’s astronomers. The “Twelve Months” of the Lüshi Chunqiu gives its signs, and the Huainanzi its place among the twenty-four.

Under the Ming and the Qing, the emperor offered a sacrifice to the Sun at the Altar of the Sun, east of Beijing, on the spring equinox, as he did to the Moon at the autumn one. A popular game survives: on the day of Chunfen, people try to stand an egg on its end, a custom that has travelled far beyond China. Many lineages also held their spring rites for the ancestors in these days, before the visits to the graves at Qingming.

How Ulune calculates it

Ulune takes the Spring Equinox as the instant the Sun’s apparent longitude reaches 0°, 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 20 March at 14:45 UT.

Correspondences