Astrologers in the Western world primarily base their interpretations on Tropical astrology, a system for measuring the stars in relation to the Earth.

The wheel in astrology is the division of constellations in the ecliptic, defined as the Sun's path perceived from Earth. Greek astrologers created the Tropical system to associate the zodiac constellations with certain times of the year, but it wasn't entirely accurate.

Since their new year began in Spring, they situated the sign Aries as the beginning of the wheel. The Greek system wasn't meant to be precise, it's an approximation to certain constellations that made it easier to associate the signs with the seasons.

The Difference between Tropical and Sidereal Astrology 

If Tropical astrology bases its calculations on the Sun in relation to the Earth, Sidereal astrology considers the fixed position of constellations; the term sidereal is defined as "of or with respect to the distant stars (i.e. the constellations or fixed stars, not the sun or planets)."

Over the last 2,000 years, the Earth's axis has tilted, or wobbled, impacting our measurement of a sign's degrees. The discrepancy between Tropical and Sidereal's systems of calculation has created various methods for calculating birth charts.

In response to a question about this disparity, Kevin Burke writes for The Real Astrology Academy that "currently, the difference between the Tropical Zodiac and the Sidereal Zodiac is about 23°. What this means is that the Spring Equinox, which occurs at 0° of Aries (Tropical) actually occurs at about 7° of the Sidereal Sign of Pisces."

Vedic, or Jyotishya, astrology uses the Sidereal system, rendering it a more accurate representation of where the stars and planets fall in one's natal chart. Many people conflate sidereal with Hindu astrology, but they're not mutually exclusive.

Cyril Fagan, an Irish astrologer of the 20th century, is primarily responsible for adapting sidereal astrology into his practice, resulting in a rise of the system's popularity in the Western world. His work creates an important distinction between Western and Eastern astrology practices; both are rooted in their cultural contexts.

Sidereal can be understood as a method of calculation, rather than being specific to the various astrological ways of interpretation. But it's also not that simple; the effectiveness and variations of the Sidereal system depend on the astrologer using it.

Incorporating the Lessons of Sidereal Astrology 

Even though Sidereal is more accurate than Tropical, many people still see the Tropical system as a valid source of insight. In my practice, I consider both. Astrology's main appeal is how nuanced interpretation can be, so why not consider it's many variations? One interpretation doesn't always negate the other; they can exist together, like pieces in a mosaic. Since when has identity, life, or destiny ever been straight-forward?

From my studies, I've discovered that your Sidereal chart can offer a deeper look into your psyche. I see the Sidereal chart as hidden potential, one that takes more effort to nurture. Tropical astrology tends to reflect our karmic lessons as well as the person we became in response to our environment. Since the system stretches the truth in order to fit neatly into the seasons, our Tropical placements reflect how we bend to circumstance.

For example, my Tropical Sun and Ascendant is in Capricorn while my Sidereal Sun/Ascendant is in Sagittarius. I faced many hardships as a child, resulting in a serious-minded and hyper-responsible personality. My environment didn't always encourage the free-spirited and adaptable aspect of my Sagittarius placements. As I grew older and more independent, I realized how much I've repressed my passion for travel, change, and new experiences due to my conditioning.

This isn't always the narrative for the distinctions between Tropical and Sidereal astrology, but it offers an interesting perspective that everyone could benefit from applying. Based on my interpretations of my client's natal charts, both Sidereal and Tropical, I have found many to be shocked, even appalled, by their Sidereal placements.

What does this mean? It can depend on the person, but I believe an aversion to a particular sign reveals a hidden psychological bias. Sidereal astrology seems to unearth latent truths about our inner self, or at least a version of the self that's harder to access and process. To me, this is worth exploring. 

Dates for Sidereal Sun Signs

It's important to remember that aspects between planets often stay the same in both Tropical and Sidereal charts; it's only the signs that shift. Sometimes the houses do as well, depending on which house system you use to calculate natal charts. Therefore, the relationships between planets remain the same, but your understanding of their expressions change.

There are variations within Sidereal systems, but the Fagan/Bradley Ayanamsha tends to be the most popular with Western Sidereal astrologers. Listed below are the dates for Sidereal Sun signs. You can also calculate your Sidereal natal chart here by selecting Sidereal instead of Tropical.

What does it mean if your Tropical and Sidereal chart features the same sign placement? There's a stronger connection to that energy, but the degrees of each placement offer different insights. Want to know more? I offer affordable readings for both Tropical and Sidereal astrology.

April 15 - May 15

Taurus

May 16 - June 15

Gemini

June 16 - July 16

Cancer

July 17 - August 16

Leo

August 17 - September 16

Virgo

September 17 - October 17

Libra

October 18 - November 16

Scorpio

November 17 - December 16

Sagittarius

December 17 - January 15

Capricorn 

January 16 - February 14

Aquarius 

February 15 - March 15

Pisces

March 16 - April 14

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