Astrological Methodology
Astrology uses two primary reference systems to locate the zodiac: the tropical and the sidereal.
A simple way to understand the difference is through mapping. One system uses a fixed directional framework, like a compass. The other tracks position relative to shifting coordinates, like latitude and longitude. Both describe the same sky, but from different reference points.
The sidereal zodiac accounts for the gradual shift of the Earth's orientation over time (known as precession). This adjustment, called ayanamsha, aligns the zodiac more closely with the visible constellations.
The tropical zodiac anchors the zodiac to the Earth's seasonal cycle, beginning at the spring equinox (0° Aries). This creates a stable, repeatable framework for interpreting planetary movement and timing.