When is the vernal equinox?

Equinox: March 21; Summer solstice: June 21; Autumnal Equinox: September 22nd; Winter solstice: 65438+February 2 1.

1, the vernal equinox usually refers to the time when the sun's apparent yellow line is at 0 on February 15 of the lunar calendar (March 20 to 2 1 day of the Gregorian calendar) every year. The time period also refers to the position where the sun is between 0 and 15, that is, from the vernal equinox to Tomb-Sweeping Day, and the Gregorian calendar is between March 20th and April 5th.

2. The midpoint of spring, also called "vernal equinox". On this day, the sun shines directly at the equator, and the length of day and night around the world is almost the same. After that, the position of direct sunlight moved northward, and the days in the northern hemisphere were long and the nights were short. Astronomy stipulates that beginning of spring begins in the northern hemisphere, and the overwintering crops enter the spring growth stage. After the vernal equinox, the direct point of the sun continues to move from the equator to the northern hemisphere, and the days in the northern hemisphere are long and the nights are short, that is, the days are longer than the nights in a day; In the southern hemisphere, the days are shorter and the nights are longer, that is, the days are shorter than the nights in a day.