The vernal equinox on March 20th or March 2nd1day in the solar calendar is when the sun is at 0. At the vernal equinox, the direct point of the sun is on the equator, and the northern and southern hemispheres are equally divided day and night.
The summer solstice is usually on June 2 1-22 of the Gregorian calendar, that is, when the sun runs to 90 degrees of the yellow meridian. On the day of the summer solstice, the position where the sun shines directly on the ground reaches the northernmost point of the year. At this time, the daylight hours in all parts of the northern hemisphere reach the longest in the whole year.
The autumnal equinox usually falls on September 22-24 of the Gregorian calendar every year. On the day of the autumnal equinox, the sun reaches the longitude 180, almost reaching the equator of the earth, and the whole world is as long as day and night.
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.