[OC] I calculated the sun sign for 10,000 birth dates in both Tropical and Sidereal astrology. 81% of people have a different sign depending on which system you use.
[OC] I calculated the sun sign for 10,000 birth dates in both Tropical and Sidereal astrology. 81% of people have a different sign depending on which system you use.
**Data source:** 10,000 uniformly distributed birth dates (Jan 1, 2000 – Dec 31, 2024), planetary positions calculated with Swiss Ephemeris (arc-second precision). Sidereal positions use the Lahiri ayanamsa (~24.21 degree correction for axial precession).
**Tool:** Python + pyswisseph + matplotlib
**What this shows:** For each tropical sun sign, the chart shows what percentage of people born under that sign have a *different* sidereal sun sign. The offset is caused by axial precession — the tropical and sidereal zodiacs were aligned roughly 2,000 years ago and have been drifting apart by about 1 degree every 72 years.
The practical result: if your birthday falls in roughly the first 24 days of your tropical sign, your sidereal sun sign is the sign before it. Only people born in the last ~6 days of each tropical sign have the same sign in both systems.
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**Data source:** 10,000 uniformly distributed birth dates (Jan 1, 2000 – Dec 31, 2024), planetary positions calculated with Swiss Ephemeris (arc-second precision). Sidereal positions use the Lahiri ayanamsa (~24.21 degree correction for axial precession).
**Tool:** Python + pyswisseph + matplotlib
**What this shows:** For each tropical sun sign, the chart shows what percentage of people born under that sign have a *different* sidereal sun sign. The offset is caused by axial precession — the tropical and sidereal zodiacs were aligned roughly 2,000 years ago and have been drifting apart by about 1 degree every 72 years.
The practical result: if your birthday falls in roughly the first 24 days of your tropical sign, your sidereal sun sign is the sign before it. Only people born in the last ~6 days of each tropical sign have the same sign in both systems.
if you want to check where your own placements fall in both systems, i built a free calculator at [synthesisastrology.com](https://synthesisastrology.com/chart?ref=reddit-dataisbeautiful) that shows tropical and true sidereal positions side by side.