The sixth day of the winter solstice solar term.

The vernal equinox is the midpoint of 90 days in spring. One of the twenty-four solar terms, every year on February 15 of the lunar calendar (about March 20 -2 1 of the Gregorian calendar), when the sun is located at 0 (vernal equinox) of the yellow meridian. 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.

The summer solstice is one of the 24 solar terms, which falls on June 2 1 or 22 of the Gregorian calendar every year. On the day of the summer solstice, the sun moves to 90 degrees of the yellow meridian (in Gemini), and the position of the sun directly on the ground reaches the northernmost point of the year, almost directly on the tropic of cancer. At this time, the sunshine time is the longest in the northern hemisphere.

The autumnal equinox is the sixteenth solar term in the twenty-four solar terms of the lunar calendar, usually on September 22nd or 23rd every year. The climate in the south began to decline from this solar term. First, the sun reaches 180 degrees on this day, pointing directly at the equator of the earth, so a day is divided into 24 hours, each 12 hours; There is no extreme day and night phenomenon in the world.

Winter solstice is an important solar term in the China lunar calendar, and it is also a traditional festival of the Chinese nation. The winter solstice is usually called "Winter Festival", "Dragon solstice Festival" and "Asian New Year". As early as more than 2,500 years ago in the Spring and Autumn Period, China had observed the sun with the earth, and determined the winter solstice, which was the earliest of the 24 solar terms, and the time was between 0 and 23 in Gregorian calendar 65438+February 265438.