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Birth Hour and the 12 Earthly Branches Explained
What Are the 12 Two-Hour Blocks?
A day is split into 12 two-hour blocks, each named after one of the 12 earthly branches: Tý, Sửu, Dần, Mão, Thìn, Tị, Ngọ, Mùi, Thân, Dậu, Tuất, Hợi (23:00-00:59, 01:00-02:59, and so on in two-hour steps). This is the actual time unit the whole star-placement calculation runs on, not the hour:minute of a modern clock. One caveat: the Tý block crosses midnight, but the charting day does NOT change within it — the day boundary is exactly 00:00 (corrected 2026-07-29, replacing an earlier 23:00 rule this site had published). Any birth between 23:00-00:59 is charted on the same solar day.
Why Birth Hour Matters More Than the Date Alone
The Life palace position is found by counting from a fixed starting palace by birth month, then rotating further by birth hour. That means birth hour is what decides which of the 12 palaces the Life palace lands on: two people born on the same date but in a different two-hour block end up with a different Life palace, which rotates every other palace along with it.
If You Do Not Remember the Exact Time
If family only recalls it loosely ("early morning", "around noon"), ask whoever was present at the birth or check a birth certificate before building the chart, rather than guessing a block. A chart built on the wrong hour produces the wrong Life palace, and every reading downstream, including an AI reading, inherits that original error.
Frequently asked questions
Does being off by a few minutes affect the chart?
Only if those minutes push the birth time into a different two-hour block — for example 22:55 and 23:05 are 10 minutes apart but fall into two different blocks (Hợi and Tý), so they still produce two different charts.
What if I was born exactly at midnight? How is the Tý block counted?
A birth at exactly 00:00 is still the Tý block, charted on that same day. The whole 23:00-00:59 span belongs to Tý and is charted on the same solar day — the day boundary is 00:00, not 23:00 as this site's earlier rule stated (corrected 2026-07-29).
What should I do if I do not remember the exact birth time?
Ask whoever was present at the birth or check a birth certificate before building the chart. A birth time that lands in the wrong two-hour block produces the wrong Life palace and skews every reading built on top of it.
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