When is the vernal equinox, summer is the solstice, and autumn is the solstice?

Vernal equinox: the fourth of the 24 solar terms, March 20th or 21; Mid-spring, the length of day and night is equal. Summer solstice: the tenth of the 24 solar terms, June 2 1 or 22; It means that the heat is coming, with the longest day and the shortest night. Autumnal equinox: the sixteenth day of the twenty-four solar terms, September 23rd or 24th; It means that in the crisp autumn, day and night are equal. Winter solstice: the 22nd solar term in 24 solar terms, which falls on 65438+February 20th or 22nd, 265438+; It means that winter is coming, with the shortest day and the longest night.

Let's talk about "vernal equinox and autumnal equinox" first. Literally, Chinese characters can be interpreted as "equal day and night". The vernal equinox is a day when spring is divided equally between day and night. The autumnal equinox is an equally divided day in autumn.

Let's talk about "winter solstice and summer solstice". Literally, it can be interpreted as "the winter night is over". The summer solstice can be interpreted as "the summer days are very long". Some people interpret "to" as "to", which is a misunderstanding. The solstice in winter never means that winter has arrived, and the solstice in summer never means that summer has arrived. If you have heard of this before and believe it, then correct it quickly so as not to be laughed at.

Here "to" means "extreme", that is, "final". What is the ending? Winter means "long nights" and summer means long days. Or to put it another way: the solstice in winter is the end of the shadow length at noon; The noon of the summer solstice is the end of the shadow length. In astronomical terms, the winter solstice is when the sun goes to the tropic of Capricorn, and it's time to turn back to the north. The summer solstice is when the sun goes to the Tropic of Cancer, so it's time to turn back to the south.