How to define 24 hours a day, how to calculate 24 hours a day

It is indeed arbitrary to divide the day into 24 hours, as long as the time of the day is a constant quantity, then how to divide it into small units of time.

It's all possible.

However, dividing the day into 24 hours has its own convenience: 24 can easily be divided into 3 or 4 equal portions, which makes it easier for people to organize their time. In addition, the division of time is related to astronomical observations in ancient and modern times, and astronomical observations generally divide the day of the week into 12 equal parts, so the division of a day into 12 equal parts or 24 equal parts is very consistent with celestial phenomena.

In addition, despite the fact that "the earth rotates."

The week is 23 hours, 56 minutes and 4 seconds", but this refers to the time it takes to observe the same star in the same position twice on the ground, which is called a "sidereal day".The most commonly used "day" is the time when the sun rises above the sky at noon twice, which is 24 hours! This day is the "Day of the Sun."

In fact, the unit "hour" was originally derived from the observed day and refers to the solar day rather than the sidereal day.

The difference between a solar day and a sidereal day is due to the difference in the distance between the sun and the stars from the earth. The solar day corresponds to people's daily habits, while the sidereal day represents the time of the earth's rotation.

Summary. It is a day during the day, a night at night, that is, 24 hours, 12 hours from 8 am to 8 pm, and 12 hours from 8 pm to 8 am, that is, the whole day and night, in layman's terms, is 24 hours from 8 am today to 8 am tomorrow.

Can you elaborate on that a little bit more?

It is a day of slag trembling during the day, a night at night, that is, 24 hours, 12 hours from 8 o'clock in the morning to 8 o'clock in the evening, and 12 hours from 8 o'clock in the evening to 8 o'clock in the morning cherry wheel, that is, the whole day and night, in layman's terms, is 24 hours from 8 o'clock in the morning today to 8 o'clock tomorrow morning.

It's not specific enough.

The Earth is the time of the year when the Earth revolves around the Sun for 1 week. While the earth revolves around the sun, the earth itself is still rotating, and the earth's rotation is one day for the earth. In the current calendar, the earth rotates 1 time and rotates simultaneously (365 days, 5 hours, 48 minutes and 46 seconds).

For the sake of calculation, the day is artificially set as 24 hours, so that every 4 years there is a leap year with about 1 day, and the leap year is 366 days. It is also called the Gregorian calendar and the Gregorian calendar. Find a clock, an hour is 60 minutes, the long is for 12, the short is for one of the numbers for the feast, for example, it is 3 o'clock in the afternoon, the long needle Zheng is against the number in 12, the short hand is against the number 3, according to 24 hours, it is 15:

00 o'clock is 3 o'clock in the afternoon, and so on, is this concrete?

The 24-hour day is now generally divided into 8 hours in the morning (including early morning and morning), 8 hours in the afternoon (including morning, noon, and afternoon), and 8 hours in the evening (including evening and evening). The specific time periods are as follows:

Morning: 0:00 to 5:00; Morning: 5 a.m. to 8 p.m.; Morning: 8 a.m. to 11 a.m.; Noon: 11 a.m. to 1 p.m.; Afternoon: 1 p.m. to 4 p.m.; Evening: 4 p.m. to 7 p.m.; Evening: 7 p.m. to 12 p.m.

In ancient times, the day was divided into 12 hours, and the earthly branch was used as the name of the hour, and there was an ancient customary name. The starting point of the hour is the noon and the night.