True Solar Time: Your Birth Hour May Have Been Wrong All Along
The birth hour reported by chart-calculation software is based on clock time. But the Earth's rotation is not perfectly uniform, and all of China uses a single time zone (UTC+8) — so your "true" birth hour may differ from the clock by nearly an hour.
A Real Case
Born on March 15, 1984, at 15:30 in Taishan, Guangdong. By clock time, this is unquestionably Shen hour (申时).
However, Taishan's longitude is approximately 112.8°E — 7.2° west of the 120°E standard meridian for UTC+8. Local solar time is naturally about 29 minutes behind. Adding the equation of time for mid-March (a systematic deviation of ±10-plus minutes caused by the elliptical orbit of the Earth) of approximately -9 minutes:
15:30 (clock) - 29 min (longitude) - 9 min (equation of time) ≈ 14:52 (true solar time)14:52 falls in Wei hour (未时) — and the Zi Wei Dou Shu chart cast for Shen hour versus Wei hour is completely different: the Life Palace (命宫) changes, the Five-Element Bureau (五行局) changes, the Life Ruler and Body Ruler change, and even the direction of the Decade Limits (大限) may reverse.
Who Needs to Pay Special Attention
- Those born near an hour boundary (within half an hour before or after an odd-numbered hour): after correction, it is very easy to cross into a different hour
- Those born in western regions: Xinjiang and Tibet are off by the equivalent of 2–3 time zones in longitude — clock time is severely distorted
- Those born overseas: must use local true solar time, and also consider whether daylight saving time was in effect that year
How This Site Handles It
Zi Wei chart calculation has true solar time correction enabled by default: select your birth city, and the system automatically converts using longitude. The results page clearly displays the entire process — "15:30 → 14:52, correction -38.2 minutes" — with nothing hidden about the methodology.
For charts born near an hour boundary, we recommend casting both the pre- and post-correction charts side by side for comparison — whichever one resembles you, the answer will be clear in the reading.