ayanamsa

An ayanamsa is a correction factor used in Hindu astrology, also known as Jyotisha. It accounts for the precession of the equinoxes, a slow, gradual shift in the Earth's rotational axis that causes the position of the vernal equinox to move westward relative to the fixed stars. Over long periods, this shift causes the tropical zodiac, which is based on the seasons, to drift apart from the sidereal zodiac, which is based on the constellations.

There are several different ayanamsas used in Hindu astrology, each calculated based on different historical observations and astronomical models. The most commonly used ones include the Lahiri ayanamsa, the Raman ayanamsa, and the Krishnamurti ayanamsa. Each ayanamsa results in a slightly different placement of planets in astrological charts, which can lead to variations in interpretations and predictions. The choice of ayanamsa can significantly impact the calculated zodiacal positions of planets, particularly the ascendant and the moon. Astrologers often choose an ayanamsa based on tradition, personal preference, or the lineage of their astrological training. The ongoing debate and differences in ayanamsa calculations are a significant aspect of astrological practice within the Hindu tradition.