Lunar observation from the first day to the thirtieth day.

A year is the time for the earth to revolve around the sun once. The total length is 365 days and 1/4 days (365.2422 days), that is, 365 days, 5 hours, 48 minutes and 46 seconds, which is called "Tropic of Cancer Year".

For the convenience of application, the calendar year does not adopt the tropic year, but adopts the whole number of days. The Gregorian calendar has an average of 365 days in a year, 366 years in leap years, one leap in four years and one leap in a hundred years. An annual calendar with full days is called a "calendar year".

The lunar calendar is based on *** 12 months in the first month, and a year is 354 days. There is a leap year every three years. The leap year is 383 days or 384 days.

One year is another cycle of climate change, the climate changes from cold to hot, and then from hot to cold; This includes the whole process of people engaged in agriculture from farming to harvesting. Therefore, since ancient times, people have taken the natural law of climate cold and hot cycles as the big unit for calculating time, and one year as the basis for making calendars.

A month is when the moon goes around the earth, that is, the new moon. The length of a new moon is 29.53059 days, that is, 29th 12: 44: 3, which is called "calendar month". As we all know, the moon is a sphere. Because it goes around the earth and follows the earth around the sun, the position of the moon to the earth and the sun is constantly changing. Sometimes there are, sometimes there are, sometimes there are no, sometimes there are many, sometimes there are few, forming a circle of the moon. When we can't see the moon, it is called the "new moon" (mostly on the first and thirtieth day of the lunar calendar). In 14 or 15 days, we will see a moon called "Wang" (mostly on 14, 15 and 16 days of the lunar calendar). From this new moon to the next, or from this time to the next, the moon revolves around the earth once, that is, for a month. We call it "the first moon".

Everyone can see the law of the moon's periodic change, so people have long regarded it as the unit for calculating days and the moon as the basis for making calendars. A month in the lunar calendar is determined according to the new moon.

A day is the time when the earth rotates once, that is, one day plus one night, that is, 24 hours. The earth is oval, so it can't shine. At the same time, only half of the earth faces the sun, which is daytime, and the side of the earth facing away from the sun cannot shine on the earth, which is night. Because the earth is constantly rotating, it forms a regular cycle of day and night.

The time when the sun is about to rise is usually called daytime, which is the beginning of the day. When the day becomes night, that is, when the sun goes down, it is called night. A day usually refers to the changing law of this astronomical phenomenon, which is easy to be grasped by people and used as the basic unit for calculating time. A day is the first unit in the calendar.

This day set by the sun is called "Sun Day". There are two kinds of solar days: "true solar day" and "flat solar day". Real solar days are long and short, because the earth's orbit around the sun is elliptical. In winter, the earth is farther away from the sun, so the revolution speed is slower. The speed of the earth's revolution is fast or slow, so the time of the day is long or short. Therefore, the time of "true sun day" is not exactly the same, and it is very difficult to use. For convenience, the calendar is not a real solar day, but a day with a constant length. This day is the average length of a real solar day in a year, which is called "flat solar day". According to the current practice, a day is divided into 24 equal parts, that is, 24 hours, and 24 hours is regarded as a day. According to the current practice, one day starts at 0: 00 in the middle of the night and ends at 24: 00 the next day. But what needs to be mentioned here is that in China's ancient traditional culture, 24 hours a day is divided into 12 hours, that is, twelve kinds of folk animals are used instead. It happens that every hour is two hours, and every hour is divided into three parts, namely the first time, the correct time and the last time. The alternating time of each day starts at midnight 1 1: 00, which is the sub-time of the next day, instead of the usual 0: 00. Therefore, at night, when 1 1: 00 arrives on time1:39 is a proton, when 1 1: 40 to12:/kloc-0. And every day is divided into morning and afternoon from 1 1: 00 to1:39, and noon from 1 1: 40 to 12: 19.

It is convenient to calculate short time in days, such as three days, five days, ten days and eight days, but it is more difficult to calculate long time, because there are months, years and centuries in calculating time.

Gregorian calendar, lunar calendar, lunar calendar

Gregorian calendar (Gregorian calendar) is a common calendar in most countries in the world, which was revised from "julian calendar". Julian calendar is the calendar decided by Julius Caesar, commander-in-chief of ancient Rome in 46 BC.

The solar calendar is a calendar based on the movement of the earth around the sun. It takes one revolution of the earth around the sun as a year. The length of a tropical year is 365.2422 days, that is, 365 days, 5 hours, 48 minutes and 46 seconds. In four years, there are 23 hours 15 minutes and 4 seconds, which is roughly equal to one day, so every four years, 1 day is added, and 366 days are obtained at the end of February, which is a leap year. But four years plus 1 day actually adds 44 minutes and 56 seconds to the tropical year. When the product reaches 128, one more day is counted, that is, 400 years is counted as three more days.

The leap year in the solar calendar stipulates that if the number of years in AD can be divisible by 4, it is considered a leap year. In order to subtract three days from more than 400 years, when an integer of the century A.D. is specified, that is, the number of years A.D. is 100, leap years can only be considered if they are divisible by 400. For example, 65,438+0600,2000,2200,2400 are leap years. In this way, three days have been cleverly shortened in 400 years. The solar calendar stipulates that every year is 12 months, and the size of the month is completely artificial. It is now stipulated that 1, 3, 5, 7, 8, 10 and1February are big months, with 3 1 day per month; April, June and September 165438+ 10 are abortion, with 30 days per month; February in a normal year has 28 days and leap year has 29 days.

The lunar calendar is based on the change of the moon phase (that is, the new moon). Because the ancients called the moon the lunar calendar, it is also called the lunar calendar, which is a pure lunar calendar. In China, the term "lunar calendar" is used, and most people call it "lunar calendar", which is wrong. The lunar calendar is not a pure lunar calendar, but a "yin and yang calendar".

The lunar calendar takes the full and short periods of the moon as one month, and 12 months as one year. However, the moon has a full moon, which is 29 days, 12: 44: 3, which is more than 29 days and less than 30 days. For convenience, the lunar calendar divides months into two types: big month and small month. 30 days a month, 29 days a month, 354 days a year.

In fact, the new moon is not exactly equal to the average of the big moon and the small moon-29 days and a half, but 44 minutes and 2.8 seconds more than 29 days and a half. So 12 moon is actually 8 hours, 48 minutes and 34 seconds longer than 354 days, and it will be 1 1 day in 30 years. Therefore, a leap year 1 1 will be inserted in the 30 years of the lunar calendar, and an extra day will be added in the 12 months of each leap year. The leap year in the lunar calendar is 355 days. So every 30 years, the lunar calendar has 19 354 days and 1 1 355 days, and the average length of a year is 354 days, 8 hours and 48 minutes. Its year is almost shorter than the tropical year 1 1 day. In three years, we lost more than a month, and 17 lost more than half a year. So with this length of time, the New Year doesn't have to be spent in winter, but it can be spent in spring, summer and autumn. Its only advantage is that the shape of the moon can be known on every date of the lunar calendar.

As a calendar, the lunar calendar is not in harmony with agricultural production and people's daily life, so in today's world, except for a few Islamic countries that are still in use for religious reasons, other countries have generally abandoned it.

The lunar calendar takes the time of the first month of the lunar calendar as the average time of the calendar month. This is the same as the pure lunar calendar, but the lunar calendar adopts the method of setting leap months and 24 solar terms, so that the average length of the calendar year is equal to the tropic year, which has the elements of the solar calendar, so it is better than the pure lunar calendar.

It is said that our ancestors used this calendar in all lunar calendars as early as the Xia Dynasty (before17th century BC). So people also call it the summer calendar. After liberation, it was still called the summer calendar. After 1970, it was renamed as the "Lunar Calendar" in China. As for the origin of the name "lunar calendar", it is probably because the country has been founded on agriculture since ancient times, so the calendar must serve agriculture.

The lunar calendar is based on the new moon. The time of the first lunar month is 29th 12 hours, 44 minutes and 3 seconds (that is, 29.5366 days), so the lunar calendar is also 30 days for the big month and 29 days for the small month, but it is not exactly the same as the pure lunar calendar, because the pure lunar calendar is arranged alternately with big and small months, and the size and month of the lunar calendar are determined by calculation.

The first day of each month in the lunar calendar happens to be a "new moon" (that is, the moon is in the middle of the sun and the earth faces the earth with half of the darkness). Sometimes there may be two big months or two small months in a row. Because the first month of the lunar calendar is slightly longer than 29 and a half days, there are about 53 big months and 47 small months in every 100 calendar month of the lunar calendar.

The lunar calendar basically takes1February as a year, but the time of 12 lunar month is 354.3667 days, which is about 1 1 day different from the tropical year. This will add 33 days every three years, that is, an extra month. In order to eliminate the extra days, one month is added every three years, which is the leap month of the lunar calendar. A year with a leap month is also called a leap year. Therefore, the lunar leap year has 13 months. As for the leap month, it is determined by the solar terms.

China calendar has a long history. "History? Yao Dian has "What is the fate, Qin Ruohao's sky, calendar like the sun, the moon and the stars, respecting the people", "The stars and birds are in the sun, Yin Zhongchun; The sun is always shining for midsummer; In the night, the stars are empty and cloudy; It is recorded that the short star in the middle of winter has six days in 360 years, and the leap month will set the age at four o'clock. Although Shangshu was entrusted by later generations, it was not enough to prove that the length of each tropical year was 366 days at that time, but for agricultural activities, "year" was the most important cycle. This is what people in primitive society got from production practice. The calendar of our country adopts the method of counting branches. Before the Eastern Han Dynasty, only days were recorded, and years were recorded after the thirty years of Jianwu (54).