How long is it from two minutes to a day?

After March 2 1 every year, when the sun shines directly on the equator and moves towards the tropic of cancer, it is the vernal equinox; After September 23 every year, when the sun shines directly at the equator and moves to the tropic of Capricorn, it is the autumnal equinox; Every year after June 22, when the sun shines directly on the Tropic of Cancer, it is the summer solstice; Every year after February 22, 65438, when the sun reaches the tropic of Capricorn, it is the winter solstice.

The fundamental reason of dichotomy is that the earth revolves around the sun while rotating, which makes the direct point of the sun do regression motion between the tropic of cancer. Because the rotation and revolution of the earth are not on the same horizontal plane, when the earth revolves around the sun, the position of the sun's direct point on the earth is constantly changing with the passage of time.

Division history from dichotomy to dichotomy

Twenty-four solar terms are the product of ancient farming civilization in China. In the historical development, cultural exchange and communication, four solar terms (vernal equinox, autumnal equinox, summer solstice, winter solstice) reflecting the return movement of the direct point of the sun were all over the pre-Qin period.

The division of the four seasons in the west is based on the dichotomy, that is, spring is divided into beginning of spring. The vernal equinox in the "vernal equinox" is also the New Year of Uzbekistan, Turkey, Afghanistan, Iran and other countries, with a history of more than 3,000 years.