Vedic Astrological History 

Tropical Zodiac? 
By Sam Geppi

What we now call the tropical zodiac is in fact a conflation of two things that, in essence, have nothing to do with each other. The earth going around the sun/the seasons –  and the precise coordinates we use to map the location of planetary orbs as they circle the earth, have nothing to do with each other.

In this video I distinguish between the solstices and equinoxes, the seasons, the calendar and the Zodiac. These things have been conflated beyond recognition and it has led to a lot of confusion.
I also describe why many Western astrologers and other scholars have found the tropical zodiac to be a highly irrational structure for erecting horoscopes. It has even led to a few Vedic astrologers to get stuck in this conflation.
However fortunately for us, the ancient Vedic scientists did not buy into this conflation and instead retained the precise, Sidereal integrity of the zodiac.

Quick Zodiac Timeline

~ Pre 10th Century BC – 12, 30° solar portions are referred to in Vedanga Jyotisha in India – All celestial portions and events are measured Sidereally. (with nakshatras).

10th Century BC – Babylonians create the Mul.Apin – with several ways to measure the sky, ALL Sidereal

~ 5th Century BC – 12, Equal 30° Sidereal signs (named Aries, Taurus, etc. in their current from) appear from the Babylonian Empire.

~ 2nd Century BC – These sidereal 30° portions find their way to Greece, where Greek astronomer Hipparchus begun mapping stars and eventually discovers the precession of the equinoxes formally.

~ 1st Century CE – Claudius Ptolemy publishes Tetra Biblos which pins the existent Sidereal Zodiacs of Greece and Egypt to the Vernal equinox. This creates the “Tropical Zodiac”, which no longer measures astronomical movements based on precise, Sidereal coordinates, but instead projects the seasonal zodiac into space in order to calculate planetary positions.

~ 2nd Century – 5th Century CE – This newly found “Tropical Zodiac” finds its way into Indian texts, mostly non astrological in nature. The most notable is the Surya Siddhanta which describes the zodiac Tropically (measured by “Signs” not Nakshatras as previously done) in reference to the Solstices.

~ Tropical / Sidereal in Vedic Astrology Texts – In spite of seeing the Tropical zodiac entering India after the Greeks pinned the Sidereal portions to the seasons, the Indians did not adapt this new tropical zodiac to their astrological practice. This is clear and not confusing at all, considering the Indians always used sidereal coordinates AND the original Babylonian sidereal signs fit almost perfectly with their 27 fold lunar zodiac. Many, if not most scholars theorize that the sidereal zodiac was “co-developed” between the Babylonians and Indians due to the obvious sharing of technologies between the 2 cultures. It was also (obviously) the right move, as the Indians created the most stable and powerful astrological system the world has ever seen.

Tropical and Sidereal Zodiacs Today – As we now know, the distance between the original, precise sidereal zodiac from Babylon and used by the Indians to this day, and the extrapolated tropical zodiac from the Greeks, that pinned the vernal equinox to the first degree of Aries, has now drifted by about 24°. It will continue to drift about 1° every 70 years for eternity.