How many times a year are there vernal equinox, summer solstice, autumn equinox and winter solstice?

The specific time of vernal equinox, summer solstice, autumn equinox and winter solstice is not fixed. The fluctuation is about three days. Equinox: March 21; Summer solstice: June 21; Autumnal Equinox: September 22nd; Winter solstice: 65438+February 2 1.

On the vernal equinox, the sun shines directly at the equator of the earth, and the seasons in the northern and southern hemispheres are opposite. The northern hemisphere is the vernal equinox and the southern hemisphere is the autumnal equinox.

On the summer solstice, the direct position of the sun on the ground reaches the northernmost part of the year, almost directly reaching the Tropic of Cancer. At this time, the day in the northern hemisphere is the longest, and the farther north it is, the longer it is.

At the autumnal equinox, the climate in the south begins to enter autumn from this solar term. On this day, the sun reaches the longitude of 180 degrees, and points directly at the equator of the earth, so the day is divided into 24 hours, each with 12 hours; There is no extreme day and night phenomenon in the world.

From winter to the sun, the sun reaches 270 degrees, and festivals are held every year on the Gregorian calendar 65438+February 2 1-23. The winter solstice marks the lowest sun height and the shortest day in the northern hemisphere.