Many people think that a sidereal 12-fold zodiac and a tropical 12-fold zodiac can both be “correct.” I disagree entirely, though I admit happily that they can both be useful, useable, effective, accurate, etc. People can use anything they like, and can even be very good at effectively using whatever they choose to use. For example, I can use a coin or a thick guitar pick to turn screws, I might even be very good at it. But that doesn’t mean that a guitar pick is just as good as a screwdriver. Similarly, I can use the sidereal zodiac astrologically. I may even be very good at it. But that doesn’t mean that the sidereal zodiac is theoretically correct, or just as good a tool as the tropical zodiac.
The “I’m OK. You’re OK” worldview appeals to their sensitivities of many people involved in astrology, and a person like me who says “No, you’re wrong” feels abrasive and archaic, I know. I apologize. People prefer the “Tropical is OK. Sidereal is OK.” answer. And there is a way to make this work. But it is not by saying “Aries can start over here, but it also starts way over there.”
One way people try to make that statement work is by saying that one “Aries” measures one thing, while the other one measures something else. They often say, “the tropical zodiac measures time, and the sidereal zodiac measures space.”
That however, is bunk, because anything that measures time must also measure space, and anything that measures space must also measure time. Why? Because time and space are inseparable.
Time and space are distinct, but inseparable. They are two properties (dharmas) of one substrate (dharmi). That one substrate, by the way, is consciousness (brahman).
Time is change.
Change requires reference points.
Space provides reference points.
Motion measures the change between the reference points.
Thus, we cannot measure time without measuring change, space and motion. We cannot measure any one of the four without measuring the other three. Consider what Einstein figured out with his Relativity calculations. This is why the Sanskrit word for time, “Kāla,” doesn’t just mean “2pm” – it means “fruition of destiny.”
And this is why it’s bunk to say that the tropical zodiac is a measure of time, while the sidereal zodiac is a measure of space. The truth is that both zodiacs measure time, change, space, and motion.
PS – There is a way for tropical to be OK and sidereal to be OK too. This is to recognize that stars are sidereal, but sunlight is not. Stars are grouped into nakshatras, and sunlight (raś) is grouped into signs (rāśī). All we need to make the two coexist is ayanāṁśa – a measure of how the star positions currently relate to the sign-positions.