Tropical Vs Sidereal

Tropical and Sidereal Zodiacs. There are two main ways to define where the signs begin, and they lead to two different zodiacs. The tropical zodiac, used in most Western astrology, ties the start of Aries to the spring equinox, anchoring the signs to the seasons. The sidereal zodiac, used in Vedic and some other traditions, ties the signs to the actual background constellations. The two zodiacs once lined up, but they have slowly drifted apart because of a slow wobble in Earth's axis called the precession of the equinoxes. Over many centuries this drift has grown to around twenty-four degrees, almost a whole sign. As a result, a person born with the Sun in late Aries by the tropical zodiac may have it in Pisces by the sidereal one. Neither system is wrong, because they measure different things. The tropical zodiac follows the seasonal relationship between Earth and Sun, while the sidereal follows the stars themselves. Knowing which zodiac a chart uses matters, since the same birth can produce different sign placements. This wiki uses the tropical zodiac, the standard in Western astrology.