True Solar Time
A method of converting clock time into the time at which the sun actually crosses the meridian, accounting for the elliptical shape of Earth's orbit and the tilt of its rotational axis. It is used for hour correction in fortune-telling chart casting.
Timeline (last 90 days)
The difference between true solar time and mean solar time (the equation of time) fluctuates by about ±16 minutes over the year, caused by the elliptical Earth orbit and the obliquity of the ecliptic.
True solar time correction is required before Zi Wei Dou Shu charting; otherwise, if the birthplace is not near 120 degrees east longitude, the hour may cross a boundary and the chart may be completely misaligned.
True solar time is the conversion of clock time into the time when the sun actually crosses the meridian; because Earth's orbit is elliptical and its rotation axis is tilted, the moment the sun reaches noon differs across longitudes within the same time zone, and a birth location on the west side of the time zone usually has a true solar time later than civil time, while the east side is earlier.
Under China's unified use of Beijing time, spanning roughly five time zones from east to west means the difference between true solar time and civil time can reach one to two hours, enough to change hour boundaries or even day-boundary attribution, thereby affecting the Four Pillars or the Zi Wei life palace.
Traditional BaZi uses true solar time, so people born at the same clock time in different cities may fall under different hour branches.
All Facts (5)
The difference between true solar time and mean solar time (the equation of time) fluctuates by about ±16 minutes over the year, caused by the elliptical Earth orbit and the obliquity of the ecliptic.
50%UnverifiedTrue solar time correction is required before Zi Wei Dou Shu charting; otherwise, if the birthplace is not near 120 degrees east longitude, the hour may cross a boundary and the chart may be completely misaligned.
50%UnverifiedTrue solar time is the conversion of clock time into the time when the sun actually crosses the meridian; because Earth's orbit is elliptical and its rotation axis is tilted, the moment the sun reaches noon differs across longitudes within the same time zone, and a birth location on the west side of the time zone usually has a true solar time later than civil time, while the east side is earlier.
50%UnverifiedUnder China's unified use of Beijing time, spanning roughly five time zones from east to west means the difference between true solar time and civil time can reach one to two hours, enough to change hour boundaries or even day-boundary attribution, thereby affecting the Four Pillars or the Zi Wei life palace.
50%UnverifiedTraditional BaZi uses true solar time, so people born at the same clock time in different cities may fall under different hour branches.
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