The differences between the sidereal zodiac of Vedic astrology and the tropical zodiac of western astrology Understanding easily the science and philosophy behind them.

1. Sidereal and
Tropical Astrology
Tropical vs Sidereal Zodiacs
By Curtis Burns of
StarWorldNews.com
In horoscopic astrology, the reading of
charts for individual persons, there are
two main zodiacs that are used: the
tropical and the sidereal.
Most Western astrologers use the tropical
zodiac, while most Vedic astrologers use
the sidereal zodiac.
The differences in the systems are not difficult to understand, and this article will explain both of
them and give a little background and speculations about what it all means.
Let’s take the chart of one person, same birth info, but different zodiac system:
• in the tropical system they would be Aries rising,
• in the sidereal system they would have Pisces rising.
How is this so?
What is a Zodiac?
First of all, we have to establish just what is a “zodiac.” The word itself means “circle of
animals” and is related to the word “zoo” or “zoology.” You’ll see that with the exception of the
Gemini, Aquarius, and Libra, the zodiac figures are all animals.
A zodiac is a plot of real estate in the sky laid out using certain markers with 12 divisions of 30
degrees making up a circle of 360 degrees. You can think of it as an arbitrary or synthetic grid
laid out on a naturalistic landscape.
The tropical zodiac is not pinned to a star, but the Sun, and more exactly the exact position of the
Sun on the first day of spring in the Northern Hemisphere. This position of the Sun is called the
Vernal Equinox, and in tropical astrology the first degree of the first sign in the zodiac, Aries, is
at that point. More on that a little bit later.

2. The sidereal zodiac uses actual fixed stars in the sky to anchor a 360 degree grid on. Different
versions use different stars (also called fiducial stars) to hang its zodiac on.
Some versions will use the stars Aldebaran (the Eye of the Bull in constellation Taurus) and
Antares (the heart of the Scorpion in constellation Scorpio) to mark out the exact axis of 15
degrees Taurus/Scorpio, and the whole 360 degree circle is laid out upon these “pegs” in the sky.
Both of these stars are in almost exact opposition to each other and are close to the plane of the
ecliptic.
Others will use the fixed star Spica to demarcate 0 degrees Libra, and so on.
It should be noted that in the sidereal system the end result is that the constellations only roughly
align with the sidereal zodiac. The constellations themselves are not in neat little 30 degrees
sections. However, the sidereal signs have somewhat of a correlation with the constellations,
while the tropical signs have no correlation with the constellations, although they freely use the
names of them.
Fixed or Moving Zodiacs
The sidereal signs are fixed, the sky you
look up to in the night sky right now is the
very same one that the ancients looked up t
at night thousands and thousands of years
ago. But the tropical zodiac is a moving
zodiac, the zero Aries point in tropical
astrology retrogrades through the entire sky
at the rate of one degree every 7
o
2 years.
while
time goes on.
not
their
themselves will alter their shape. This is called proper motion
So since the last time the zodiacs were
exactly lined up in 290 AD, they have
moved twenty-four degrees out of
alignment. So this is how one chart can be read with Aries rising,
the other system will read it as Pisces rising, and so forth for every
planet and point in the chart, and the difference will only increase as
As a side note, I am not saying that the stars of the constellations do
move move in other ways. They actually do shift about within
constellations. Over the course of millennia the constellations
.
Precession
Why Does the Vernal Equinox Move?

3. To understand this you need to understand a little
bit of of the celestial coordinate system. The
Celestial Equator is the Earth’s equator projected
out into space, and the Ecliptic is the path of the
Sun, Moon and planets as seen from the Earth’s
surface. The Vernal Equinox, or the point
regarded as zero degrees Aries in the tropical
system, is the exact intersection of the celestial
equator and the ecliptic.
The Vernal Equinox moves because the Earth is
tilted on it’s axis and it has a motion like a top,
which is called precession. So as the Earth’s axis
precesses over time, so will the Vernal Equinox,
which pushes the entire zodiac along with it,
changing slowly over the centuries. This also is
famously known as the precession of the
equinoxes, the entire cycle of which takes 25,800 years.
Earth to Sun, Earth to the Stars Relationships
The tropical zodiac is based on the relationship of the Earth to the Sun and has no relationship to
the constellations which its signs are named after, while the Vedic sidereal is based on the
relationship of the Earth to the stars and each sign is directly connected to the constellation
which it is named after.
The tropical zodiac attunes with the Earth’s seasons, while the sidereal zodiac attunes to
something far vaster, much less attuned to normal considerations of time, space or causality due
to its incomprehensible immensity, perhaps closer to the Divine Itself.
Seasonal and Astrology Sign Correllations
In Western astrology the progression of the seasons is compared to the succession of each sign.
That is, the first sign Aries is compared to the spring, where seeds are planted, then the 30 days
of Taurus where they are carefully watered and cared for, then during the 30 days of Gemini
there is a lot of moving about during the ramping up of the summer season of peak activity, and
then the 30 days of Cancer in the summer when Mother Nature is at the peak of her activity, and
so on moving through the harvest and winter season with the other signs. There is a seasonal/life
correlation with every sign.
However that system is literally turned on it’s head in the Southern Hemisphere of the Earth.
When the Northern Hemisphere is in the peak of summer, the Southern Hemisphere is at the
absolute coldest and darkest of winter; which sort of negates their attempts at creating a heavenly
and earthly synchronicity. A lot of western astrologers simply gloss over this point.
What do the different zodiacs mean?

4. In my experience the sidereal chart resonates with the deeds and actions of an individual, while
the tropical zodiac resonates with thoughts and feelings of an individual.
Because the sidereal zodiac does not move, you could say that it penetrates on a deeper level in
human experience. The tropical zodiac, because it is the moving zodiac affects more transitory
and changeable aspects of human life, the mental and emotional patterns of an individual, their
subjective responses to life.
As an example, a person that has the Sun in Gemini in a tropical chart would be intelligent,
inquisitive, and typically bright in his attitudes; it highlights their psychological proclivities. A
sidereal Sun in Gemini however would manifest his Gemini through his deeds: i.e. he would be a
teacher, a news reporter, or a delivery person. The sidereal has a more concrete and measureable
effect to it.
Sidereal astrology since it is based more on our actions as individuals, it is therefore a karmic
type of astrology, since karma by definition is the result (positive or negative) of our actions.
We could call it the astrology of cause and effect. Maybe we could call tropical astrology to be
the astrology of the mind, since the relativistic perceptions and reactions that it governs occur
primarily in the field of the mind.
Zodiac Comparison
Zodiac Based On Relationship Of Moving or Fixed Emphasis
Tropical The Earth to the Sun Moving Thoughts and Feelings
Sidereal The Earth to the Stars Fixed Deeds and Actions
Experiences with Zodiacs
Western astrology itself claims to be more psychological than predictive, yet I’ve found great
depth of psychology in the sidereal positions myself, in addition to the more concrete types of
information. One might say “actions speak louder than words.”
Through hundreds of chart readings I’ve discovered that the sidereal system carries over very
well through the deeper layers of chart reading: the house rulership system, the navamsha and
other varga charts; and it is also the basis of the powerful dasa prediction system.

5. But if you try to apply those same techniques to a tropical chart, the effectiveness begins to
breakdown very quickly. It is my opinion that in order to compensate for a weak sign/house
system the Western school had to develop a more complex planetary aspect system and places
more emphasis on it.
It is also my opinion that the tropical system is not necessarily a destiny and fate measuring
system as it is more actually a calendrical system used to measure time in a very worldly sense;
how the seasons affect and determine human life.
I’m sure that a lot of tropical astrologers will very strongly disagree with me, and many have.
But I have to ask if any of those astrologers did an actual side by side comparison of tropical and
sidereal charts with a series of clients over any length of time. Most of them have not, they just
assume that the tropical system is just as good as the sidereal, which is what I used to think until
I actually started to experiment
with the Vedic system.
I was a tropical western astrologer
for ten years, and then at the
prompting of some lectures I
heard through Project Hindsig
a research project at re-translating
some of the ancient Greek and
medieval astrological texts, I
started to investigate the
Vedic/sidereal system.
ht,
The most significant thing I
discovered using sidereal charts
right away was their simplicity
and directness, where I did not
need to resort to complicated and
obscure calculation methods to
interpret a chart; they just spoke
very cleanly through the planetary
sign, house and traditional rulership system; and using just the seven classical planets (no
Uranus, Neptune and Pluto.)
Not only was it clear in exposition, but quite relevant to the client, whereas western techniques
(especially such as the newly rediscovered medieval techniques) wouldn’t be very clear or
effective. At any rate, this is my experience and my conclusions about the matter.
Neo-Vedic Tropicalists
There is subset of Vedic astrologers who have switched over to the tropical system, citing
passages from ancient Indian astronomical texts such as the Surya Siddhanta and the works of
Varahamihira that we’ve been doing it all wrong and that we need to use tropical charts.

6. Albeit those astrologers claim to have put their findings to the test, the fact that one’s rationale
comes from some kind of “source” material alone is not a good justification. Experience has to
trump doctrine. If some ancient book with a venerable tradition told me that I should meditate in
the middle of a busy intersection at noon, does that make it right? Obviously no.
Nevertheless, my experience gives great validity to the sidereal system for simplicity,
transparency and uncompromising directness regarding the person and circumstance in their life.
I may actually get to reading the Surya Siddhanta though, someday.
I prefer Occam’s Razor: the most direct answer is usually the best. I don’t mix tropical and
sidereal zodiacs, which some astrologers do.
My goal is to deliver the best, most accurate and most useful system for myself and my clients,
which is why I’ve become a siderealist/Vedic astrologer. It makes one stand out like a black
sheep at astrology meetups and such, but we have to honor the convictions of our hearts.
Part of the reason for the creating and maintaining of this website is to provide some sort of
empirical record of correlations of astrology in general to a skeptical world, as well as for
sidereal calculations.
Vedic Astrology’s Own Problems
As another aside, I would say also that Vedic astrology as a whole has probably more than its
share of interpretive garbage to it. There are thousands of yogas (planetary combinations) and
aphorisms that are extremely fatalistic, negative and don’t work at all. I don’t even use the
Vedic moon mansions (called nakshatras) in natal interpretation because I have yet to see any
substantive contribution from them to any chart reading. These traditions have perpetuated to
this day it seems simply because they are in a “classic text” and people (astrologers) assume
them to be accurate.
So, just because something is in a ancient book doesn’t
necessarily mean it’s worthwhile.
Zodiac History Speculations
Claudius Ptolemy
The tropical zodiac came into use during the time of
Ptolemy with his book the Tetrabiblos, and it was during
that time (the middle of the second century AD) that the
tropical and sidereal zodiacs were in very close
alignment, so the differences in zodiacs was not a big
issue at the time. Ptolemy himself was not an astrologer,
more of a compiler of esoteric information at the Library
of Alexandria in Egypt, his authoritativeness in astrology

7. alone is not firmly estabished.
Then came the burning of the great Library by marauding Christians, followed by the Dark Ages
of Europe. There was no one really to take up the torch and what could have been an innocent
enough error at the time, then became regarded as gospel truth.
It was the Islamic world that then took up the torch of integrity for science (including astrology)
and I still need to do more research on the Middle East’s contributions to astrology, especially
regarding zodiacs.
Conclusions
For all intents and purposes, we can say that the tropical zodiac is more psychological in it’s
results, while the sidereal zodiac seems to focus more on the level of what we do and the karma
created thereby.
There are a lot scientific, religious and political beliefs today that are based on assumptions,
biases, and prejudices; anything except facts, empirical proof, or real analysis. Why wouldn’t it
be much different for the world of astrologers?
Every astrologer needs to use the system that works best and has proven itself to be so through
some sort of rigorous empirical analysis. My allegiance will always be to the system which
yields the best results.
This article is a summation of my speculations. I am not an authority on the matter, I’ve just
done a lot of chart readings and had opportunity to compare methods since the early 2000’s, and
I’ve done a lot of reading about these issues as I’ve started to become a teacher of astrology
myself.
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