In different parts of the earth, sometimes a day and night means more than 24 hours. For example, in the Antarctic and the Arctic, sometimes a year is a big day and night, half a day and half a night. The earth revolves around the sun while rotating. The rotation of the earth around its axis from west to east is called rotation. One revolution of the earth is a day and night, with 24 hours.
The movement of the earth around the sun is called revolution, and the earth makes one revolution, that is, one year. An important feature of the earth's revolution is that the orbital plane of the earth's revolution always keeps an angle of 66.5 with the earth's axis, and the north pole always points to the vicinity of Polaris.
Because of this important feature, during the earth's revolution around the sun, the sun sometimes shines directly in the northern hemisphere, sometimes in the southern hemisphere, and sometimes at the equator. During the year, the direct point of the sun always moves back and forth between 23.5 north latitude and 23.5 south latitude.
Related information:
The ancient working people divided a day and night into twelve periods, and each period was called an hour. Twelve o'clock can refer to either a day or any time. Twelve o'clock was created by the ancient working people in China according to the natural laws of the sun, the changes of the sky and the daily production activities and living habits.
This is the twelve-hour system used in the Western Zhou Dynasty. In the Han Dynasty, it was named Midnight, Crow, Pingdan, Sunrise, Food Time, Horn, Japan-China, Sundial, Sunset, Dusk and Man's Decision. It is also expressed by the twelve earthly branches, and it is the child time from 23: 00 to 1 at midnight, the ugly time from 1 to 3: 00, and the Yin Shi time from 3: 00 to 5: 00, which are recursive in turn.
Twelve o'clock consists of twelve specific time nouns. People can find the source of these words from the ancient books of China in the pre-Qin period. Before the Han Dynasty, these appellations were different. Until the early Han Dynasty, China implemented the taichu calendar Law. "Twelve o'clock a day, the main branch is the subject."
(Zhao Yi's Examination of Jade Cong, Volume 34) Basic stereotypes and naming. The twelve o'clock calendar is unique and has a long history. It is an outstanding contribution of the Chinese nation to the astronomical calendar of mankind and one of the splendid treasures of Chinese culture.
At twelve o'clock, the twelve-point regimen of Huangdi Neijing is integrated into people's daily life through timing tools, reminding people of scientific regimen at any time and letting everyone know how to use Huangdi Neijing to carry out regimen and popularize scientific regimen, which is undoubtedly of revolutionary significance for improving people's physique and improving people's quality of life.
12 hour is equivalent to 24 hours and 2 hours per hour. It is clearly pointed out in the New Tang Calendar that "the ancient calendar divides the day and begins at midnight", and the midpoint of midnight, that is, today's zero hour (24: 00), is the beginning of the day.