- Tropical and sidereal zodiacs use different reference frames.
- Neither setting is a hidden correction inside the other.
- Interpret a chart consistently within the selected tradition.
The tropical zodiac
The tropical zodiac anchors zero degrees Aries to the March equinox and divides the ecliptic into twelve equal thirty-degree signs. Western tropical astrology interprets signs through this seasonal framework even though astronomical constellations vary in size.
ZodiacJoy uses the Western tropical zodiac unless a page explicitly states otherwise.
The sidereal zodiac
Sidereal systems relate the zodiac to stellar reference points and apply an ayanamsha, an offset accounting for precession. Different ayanamshas can produce slightly different degrees, especially near boundaries.
Vedic astrology commonly uses a sidereal zodiac, though its interpretive tradition includes much more than switching a setting in a Western chart.
Why placements change
The current offset between common tropical and sidereal calculations is large enough that many planets move into the previous sign in a sidereal chart. The planet's astronomical location has not changed. The coordinate framework used to label that location has.
Houses and aspects may also differ depending on the broader calculation choices being compared.
How to compare responsibly
Do not combine tropical sign meanings, sidereal placements, and techniques from different traditions without understanding their assumptions. Choose a coherent framework, learn how it handles rulers, houses, timing, and interpretation, and evaluate the chart within that system.