Western Astrology uses the spring equinox as a point of reference in the calculation of the chart. According to this system, the Sun enters Aries on the spring equinox. While this was true 2,000 years ago when Western Astrology was born, it is no longer astronomically accurate.
Other differences between Vedic and Western Astrology
In Western Astrology the zodiac is divided into 12 constellations. In Vedic Astrology the zodiac is divided into 12 constellations and also into 27 lunar constellations, called Nakshatras.
Each Nakshatra is related to a certain deity and shares into that deity’s symbolism and mythology. The planets to be found in that Nakshatra and what they represent in the chart relate strongly to the myths of the Nakshatra.
Vedic Astrology also uses something called Dashas, or planetary periods. Depending on the nakshatra in which the Moon is found at birth, the life of the person is divided into planetary periods. The Dasha system is what makes Vedic Astrology a great predictive tool and it is something that cannot be found in Western Astrology.
Western Astrology places a strong emphasis on the psychological nature of the individual. Vedic Astrology also considers one’s psychology, one’s karmic tendencies, but gives equal attention to when such tendencies are likely to manifest.
Another difference between Vedic and Western Astrology are the subcharts (also known as harmonic charts). These are sub-divisions of the main chart and are used to reveal details about relationships, career, health, family, finances, spirituality, etc. The most important harmonic chart is the Navamsha. The Navamsha is as important in chart analysis as the natal chart. Some say that if the natal chart is the tree, the karma we brought with us into this lifetime, the Navamsha represents the fruits of the tree.