The tropical reference used here
The tropical zodiac anchors 0 degrees Aries to the March equinox and continues around the ecliptic in twelve equal 30-degree intervals. The sign labels therefore remain tied to the seasonal equinox/solstice framework. This project converts supported bodies to the true ecliptic and equinox of the requested date, then classifies that tropical longitude without an ayanamsha.
What a sidereal calculation changes
A sidereal calculation applies a stellar reference and an ayanamsha—the selected angular offset between tropical and sidereal zero points. Sidereal traditions do not all use the same ayanamsha, so “sidereal” alone is not enough information for an exact comparison. A different sign can be the expected result of the configured offset.
This site does not calculate or recommend an ayanamsha. Users seeking a sidereal result should use a tool that names its reference and version, then avoid mixing that output with tropical labels from this project.
What does not change
The birth event should still resolve to the same real UTC instant when both tools use the same date, time, place and historical timezone. The astronomical body and coordinate origin also need to match. Changing the zodiac origin is separate from changing geocentric to topocentric position or changing how daylight-saving ambiguity is resolved.
How to compare two results cleanly
First confirm the UTC instant. Next confirm tropical or sidereal; if sidereal, record the ayanamsha. Then compare geocentric/topocentric, apparent/geometric and ecliptic conventions. Finally compare the unrounded longitude rather than only the sign label or rounded degree.
- This project: Western tropical, twelve equal 30-degree signs.
- Planetary origin: geocentric apparent under the documented production method.
- Rising: eastern local-horizon intersection; no house system.
- Interpretive claims are outside this coordinate-system guide.
A neutral scope note
The project documents which convention it calculates so a user can reproduce the answer. It does not claim that a zodiac framework is scientifically established, nor does a calculated label determine identity or predict an event. Astrology is not scientifically established; interpretations are for entertainment and self-reflection.