Sidereal zodiac and tropical zodiac
By Krishna Wiuker

One of the main differences between Vedic and western astrology

This past march 20th 2014 was the day of the equinox, which marks the beginning of spring for the northern hemisphere and of fall for the southern one.
The equinoxes are the days in which the two poles of the earth are at the same distance from the Sun. The Sun is aligned with the equatorial plane of the earth. This event happens twice a year. Those are the moments when the day and night have equal length.
In common western astrology, this is considered as the beginning of Aries, meaning when the Sun supposedly aligns with the beginning of the constellation of Aries.
But in fact, this is a misconception.

That DOESN’T happen literally.

If we observe the sky or through a basic astronomical calculation we can see that at this time of the year the Sun is almost in the beginning (6 degrees) of the constellation of Pisces, meaning, that seen from the earth, the Sun is aligned with the constellation of Pisces behind it. This is actually quite far from the beginning of Aries, as we can see in the picture, which is a modern astronomy planetarium simulator. We will see the Sun entering the constellation of Aries only from April 14th.

In this picture, we can observe the Sun and the constellations on the sky on March 20th 2014. The red line indicates the ecliptic, the path of the Sun in the sky as seen from earth. (This picture corresponds to the sky as seen from the northern hemisphere. If you are in the south, you will see it all inverted, upside down, right side left.)
That misunderstanding about the Sun’s constellation placement happens because of a phenomena called precession of the equinoxes. Due to the tilt of the earth axis, every year when the equinox happens, it does 50.3” seconds or arc earlier in the sky.
In ancient times, there was a time when the equinox did happen at the beginning of Aries, and that was in the year 285 AD. Since then, the equinox has been moving backwards in the zodiac with a speed of one degree every 72 years approximately. Nowadays the precession has gone about 24 degrees backwards and it happens in the earlier portion of Pisces, aprox 6 degrees.
The type of zodiac that western astrology commonly uses is called the “tropical” zodiac, because it is based in the equinoxes, the seasons and the placement of the Sun relative to the earth equator and to the parallels of the tropic of cancer and Capricorn, and from there the confusion arises, because the projection of the Sun into the earth on those tropics has for long time not correspondence with the constellations of the same names (cancer and Capricorn)
On the other hand, Vedic astrology has always considered the precession and calculates the difference between the equinoxes and the placement of the Sun and the rest of the planets in relation to the stars and constellations in the sky.
That’s why the zodiac used by Vedic astrologers is called the “sidereal” zodiac, the word sidereal coming etymologically from the meaning “in reference to the stars”.
This difference of degrees between the two zodiac systems is not only applicable to the Sun sign, but also to the moon, the ascendant and the rest of the planets. Doing that, the birth chart is quite different.
Nevertheless, the tropical zodiac has its validity for certain areas of astrology, no doubt, but it is inaccurate and misleading in others. We have to understand the differences between these two zodiacs systems and what each of them is representing.
The tropical zodiac is the proper one if we want to understand the relation between the Sun and the earth at any time of the year, and especially to determine the beginning and ending of the seasons, which definitely have an influence on the life on earth. Astrologically the tropical placement of Sun and planets does have some influence in the personality and psychology trends of an individual, more from the point of view of the ego.
Even tough many vedic astrologers completely deny the use of the tropical system, we can see that its use has some validity to show certain dimensions of the influence of planets. The division of the circumference of the ecliptic into 12 sections can actually be done from different starting points of the sky, and it will be helpful to understand different dimensions of a birth chart. Even when we use the sidereal zodiac, we could use the tropical one as a sort of a “house system” when the first house always has a parallelism with Aries, the second with Taurus, and so on.
Even in vedic astrology, the first house, whatever the sign it is, has some characteristics of Aries and so on.
So in this way, if we take the equinox as a starting point (equivalent to an alternative ascendant) we can divide the rest of the sky into 12th equal sections and relate them with Aries, Taurus, etcetera, even though those do not correspond with the actual constellations of those names.
But, on the other hand, when we want to understand the influence of the constellations on the way the planets manifest, the use of the tropical zodiac can be inaccurate. We would commonly make important astrological mistakes or at least it would limit the precision of a chart interpretation and prediction if we rely in the tropical signs alone.
For example, we cannot attribute characteristics of the constellation of Aries to the Sun, and forget that in fact it is located in front of the constellation of Pisces. Aries and Pisces have totally different characteristics and energies and represent very different things and dimensions of experience. The same with the Moon, the ascendant and the rest of the planets. It is very important to understand and analyze their Sidereal placement.
If we want to know their actual placement in the sky, in reference to the actual star constellations, we would have to subtract about 24 degrees from their tropical placement.
According to Vedic astrology, the sidereal is the one that relates to the Soul’s journey through the different life times and the type of karma that it brings into this world to be experienced, and also for accurate predictions about future events.
Nevertheless, the tropical zodiac has its uses. Some astrologers who studied and use both systems claim that the tropical one is helpful to understand the personality and psychology of an individual, but inaccurate at the time of making predictions or timing of events and the vedic/sidereal astrologers are very good at.
Even in classic vedic Jyotish scriptures, like for example Surya Siddhanta, mentions the use of tropical zodiac to calculate certain Sun influences, which re very important for the Vedic life, like the ritus (seasons) and the Ayanas (uttarayana and dakshinayana, the Day and night of the Devas, beginning and ending of the northern or southern movement of the Sun for 6 months). The Ayanas are very important in Muhurtha or vedic electional astrology, especially for the performance of some of the vedic rituals, building of Temples, yogic practices and even for choosing the time of leaving the physical body!
There are still many Vedic astrologers, short of astronomical understanding, that blindly hold to the use of sidereal zodiac for the calculation of Ayanas.
There is a common widespread misuse of the sidereal zodiac even by many Priest in India, when they celebrate the “makara shankranti” of ingress of the Sun in the constellation of Capricorn, (January 14th) as an indicator of the beginning of the Uttaraayana (northern course of the Sun) when in fact the Sun starts to move northwards from about December 21st, which corresponds to the ingress into tropical Capricorn, and not sidereal Capricorn.


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