The vernal equinox is the midpoint of the ninety days of spring. It is one of the twenty-four solar terms, and the sun is located at 0° of the yellow meridian (the vernal equinox) around March 20 on the Gregorian calendar every year.
The equinox is the day the sun shines directly on the Earth's equator, the northern and southern hemispheres have opposite seasons, the northern hemisphere is the spring equinox, in the southern hemisphere is the fall equinox.
It is worth noting that the days are getting longer from the winter solstice across the Northern Hemisphere, but the days are longer than the nights only from the spring equinox; the days are getting shorter from the summer solstice, but the days are shorter than the nights only from the fall equinox.
On the vernal equinox, the sun shines almost directly on the Earth's equator, and day and night are almost equal in length around the globe.
The vernal equinox is also the New Year in Iran, Turkey, Afghanistan and Uzbekistan, with a history of 3,000 years.