World time zone time difference of astronomical calendar

The time used in fortune telling is astronomical time (visual solar longitude time), while the time recorded in the minds of ordinary people is clock time, which is the average solar time in the artificial standard time zone. If you are born at a certain time The timing of the head and tail is often wrong due to the "true solar time difference". The world is divided into twenty-four time zones, with the longitude divisible by 15 as the central meridian of the region, and each time zone occupies 15 degrees of longitude. In areas east of the central meridian of the time zone, time is added, and in areas west of the time zone, time is subtracted by 4 minutes per degree.

China is divided into five time zones:

(1) Central Plains Time Zone (East Eighth District): 120 degrees east longitude is the central meridian.

(2) Longshu Time Zone (Eastern Seventh District): Take 105 degrees east longitude as the central meridian.

(3) Xinjiang-Tibet Time Zone (Eastern Sixth District): Take 90 degrees east longitude as the central meridian.

(4) Kunlun Time Zone (Eastern Zone 5): Take 75 degrees east longitude as the central meridian.

(5) Changbai Time Zone (East Nine District): Take 135 degrees east longitude as the central meridian.

The "standard time" of a time zone is just a unified time in a large area and an "artificial" time that everyone adheres to. It is not the "local time (LMT) of every location in the time zone." "--the true longitude time. The longitude of the place of birth should be used to add or subtract from the standard time of the large area where the person was born. This principle applies to any place in the world.

For example: the Central Plains time zone includes Inner Mongolia, Liaoning, Hebei, Shanxi, Shandong, Henan, Anhui, Jiangsu, Hubei, Hunan, Jiangxi, Zhejiang, Fujian, Guangdong, Hainan, Hong Kong, Macau, and Taiwan. When the clock hits 12 noon in this large area, only the location located on the 120th east longitude line is 12 o'clock, and other places are less than or more than 12 o'clock. For example, Hong Kong is located at 114 degrees 10 minutes east longitude, which is 5 degrees 50 minutes west of 120 degrees east longitude. Its true longitude is 11 hours 36 minutes 40 seconds.

Mean solar time and true solar time

The "mean solar time" of 24 hours a day in clock time is artificial. It is assumed that the earth's rotation and revolution around the sun are in a perfect circle. It is just a "unified" time set by the government for the convenience of administrative measures. In fact, the rotation and revolution of the earth, due to the relationship between the ecliptic equator, are not 365.25 days a year and 24 hours every day. They are only on April 25, June 14, September 1, and December 24 of the solar calendar each year. It’s just 24 hours, and the remaining 361 days are either more or less. This error is called "true solar time difference". The "World Nautical Calendar" indicates the time difference between the true solar day and the mean solar day every day. There is also a kind of "wartime" in artificial time, also known as "summer time" and "daylight saving time". In some countries and local governments, in summer, because the sun rises early, sets late, and the days are longer, in order to make full use of sunlight and save electricity, the work and rest time is advanced by one hour (the clock is set forward by one hour). Due to the above three time differences, it is not easy to get the accurate astronomical time of birth. It is especially difficult to calculate the horoscopes of foreigners, because the time system in some areas implements winter time, or adopts Greenwich Mean Time (GMT), or adopts local time systems, which are not uniform. Numerologists must first inquire about the time system in that area. , so as not to make mistakes.

If the birth time is at the junction of solar terms or Zi hours, the time difference must be calculated accurately. Otherwise, not only the time will be wrong, but also the birthday, birth month, and birth year may be full due to an incorrect hour. All wrong.