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The Sidereal and Tropical Dichotomy in Astrology

CEO Khai Intela
Astrology has been a subject of fascination for centuries, captivating the minds of people across cultures. From the worship of heavenly bodies to the intricate calculations based on celestial movements, astrology encompasses a wide range...

Astrology has been a subject of fascination for centuries, captivating the minds of people across cultures. From the worship of heavenly bodies to the intricate calculations based on celestial movements, astrology encompasses a wide range of traditions, systems, and beliefs. One intriguing aspect of astrology is the division of the ecliptic into twelve "signs," which can be classified under two main systems - sidereal and tropical astrology.

Understanding Sidereal and Tropical Astrology

In sidereal astrology, the division of the zodiac signs is based on the observable sky and takes into account the Earth's axial precession. This means that the signs are aligned with the constellations, which appear to move backwards by about 1 degree every 72 years. On the other hand, tropical astrology defines the zodiac signs based on the March equinox, with 0 degrees of Aries always coinciding with this celestial event.

The fundamental difference between the two systems lies in their reference points. Sidereal astrology aligns signs with constellations, while tropical astrology takes the seasons into consideration. As a result, these systems have gradually drifted apart over the centuries.

The Impact of Axial Precession

Axial precession is the gradual change in the Earth's orientation, causing the position of the March equinox to shift over time. This phenomenon has a significant impact on the alignment of signs and constellations. While the sidereal system accounts for this precession through corrective systems known as ayanamsas, tropical astrology does not consider it.

It is important to note that most tropical astrologers consider the zodiac of the Northern Hemisphere to be applicable worldwide. However, a small number of practitioners adjust the zodiac to reflect the seasons in the Southern Hemisphere. This means that in these cases, Libra replaces Aries as the sign that coincides with the spring equinox.

The Influence of Ayanamsa Systems

Various ayanamsa systems are used in different branches of astrology. For instance, Hindu astrology, also known as Vedic astrology, utilizes the Lahiri and Raman ayanamsas. The Fagan-Bradley ayanamsa, on the other hand, is a prominent system used in Western sidereal astrology. These systems help astrologers maintain the alignment between signs and constellations, accounting for the Earth's axial precession.

Symbolic Constellations in Sidereal Astrology

While traditional astrology divides the ecliptic into 12 equal sections for the zodiac signs, some sidereal astrologers take a different approach. They define signs based on the actual width of individual constellations and include constellations that are disregarded by the traditional zodiac but still interact with the ecliptic. The boundaries of these constellations were established by the International Astronomical Union in 1930 without considering astrological purposes.

Exploring the Astronomic Zodiac

As the Sun moves through the ecliptic, it passes through the constellations of the zodiac. The specific dates of entry into each constellation can differ depending on the system used. In the tropical zodiac, the dates range from March 22 to April 20 for Aries, while the sidereal zodiac based on the Lahiri ayanamsa has the dates of April 14 to May 14 for the same sign.

Sidereal and tropical astrology Precession of equinoxes, the changing position of the vernal equinox over the course of about 25,800 years. The yellow line represents the ecliptic, the apparent path of the Sun over an Earth year, while the purple line denotes the celestial equator.


Astrology is a complex and multifaceted subject, with sidereal and tropical astrology representing two distinct approaches to understanding the zodiac signs. While sidereal astrology accounts for the Earth's axial precession and the alignment between signs and constellations, tropical astrology is rooted in the seasonal cycle. Regardless of the system one follows, astrology continues to captivate our imagination, offering insights into our lives and the world around us.


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