When astrology is mentioned it conjures up images of the constellations that we gaze upon in the night sky. As the Moon affects the tides of the rivers and oceans, and the Sun affects whether it is day or night, astrologers believe that the celestial bodies in our universe also have an affect upon Earth and influence the lives of its inhabitants.
As astrology was being developed in ancient times by the Babylonians and Hellenistic Greeks astrologers based what is called Tropical Astrology on the path of the Sun traversing the Earth in relation to the change of the seasons. They used the tropics as their reference points. This type of astrology is widely used in the Western world.
In contrast, Vedic (Hindu) astrology, which is known to be the oldest type of astrology, uses what is called Sidereal Astrology, based on planets passing through the current or true positions of the fixed stars. This eliminates the need to recalculate due to precession (the gradual shift in the orientation of Earth’s axis of rotation) which has occurred over time.
Tropical Astrology is largely exclusive to Western astrologers. However some Western astrologers choose to practice Sidereal Astrology. These astrologers take the view that Tropical Astrology is no longer relevant because it does not align with the actual position of the stars; having a basis which was developed prior to the consideration of precession.
However, in spite of precession Tropical Astrology remains unchanged, as it is based on the Earth's and our relationship to the sun, and not to the stars. The names of the zodiacal constellations that became our ‘sun and star signs’ are, according to tropical astrology, intended to suggest the characteristics of (the sun in) each constellation of the year.