How to understand "vernal equinox and autumnal equinox, equal day and night"?

The spring equinox solar terms are characterized by almost equal day and night and abundant rain. At the vernal equinox, the sun shines directly on the equator. On this day, the length of day and night in the northern and southern hemispheres is the same, and both day and night are 12 hour. There will only be vernal equinox and autumn equinox in a year. The vernal equinox is one of the solar terms reflecting the changes of the four seasons and the fourth of the 24 solar terms. The vernal equinox, summer solstice, autumn equinox and winter solstice are in the middle of each season. At the vernal equinox, the sun shines directly on the equator, and the time between day and night is equal all over the earth, so the ancient vernal equinox and autumn equinox are also called "day and night equinox".

Vernal equinox custom:

1, vertical eggs, "When the vernal equinox arrives, the eggs will look good." The vernal equinox is the day when yin and yang are half and half, and it is the easiest to lay eggs. The reason is that the vernal equinox is a day in which day and night are equal in the northern and southern hemispheres, and the earth's axis is tilted by 66.5 degrees, which is in a relatively balanced state with the earth's orbital plane around the sun, which is very conducive to laying an egg. Eggs will thrive in spring.

2, flying kites, clear skies in Ran Ran, breezes, the most suitable for flying kites. You can fly a kite to exercise your muscles and eliminate "spring sleep" and "depression".

3, eat spring vegetables, "eat spring vegetables at the vernal equinox." "Spring vegetable" is a kind of wild amaranth, which villagers call "Artemisia chun". Spring vegetables collected on the day of the vernal equinox are usually boiled with fish fillets at home, which is called "spring soup".

4. Send spring cattle, the vernal equinox is coming. At that time, there will be a picture of sending spring cattle door to door. The picture is printed with red paper or yellow paper on the lunar solar terms all the year round, and also printed with farmers' ploughing patterns, which is called "Spring Cattle Map".

5. Stick the sparrow's mouth. According to custom, farmers have a holiday on the vernal equinox. Every family should eat glutinous rice balls. Ten, twenty or thirty glutinous rice balls that don't need wrapping should be cooked and put on the edge of outdoor fields with thin bamboo forks, which is called sticking sparrows' mouths to prevent birds from damaging crops.

6, Spring Festival, February vernal equinox began to sweep graves to worship ancestors, also known as the Spring Festival. Before sweeping the grave, a grand ancestor worship ceremony should be held in the ancestral hall, and the drummer will play music, read the eulogy and quote three praises.