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Ayanamsha
Open a Western birth chart and a Vedic birth chart for the same person born at the same moment. The planets will be in different signs. Saturn might be in Aquarius in one and Capricorn in the other. This is not an error. It reflects a fundamental disagreement about the starting point of the zodiac.
Two Zodiacs§
The zodiac is a 360° band around the sky divided into twelve 30° segments called signs. The question is: where does Aries begin?
Tropical Zodiac — Western Astrology. Aries begins at the vernal equinox — the moment each year when the Sun crosses from the southern to the northern hemisphere. This point moves backward against the fixed stars by about 50 arc-seconds per year (precession of the equinoxes). The tropical zodiac tracks the Sun's seasonal relationship with Earth, not its position against the stars.
Sidereal Zodiac — Jyotish. Aries begins at a fixed point in the sky defined relative to specific stars. As Earth precesses, the sidereal zodiac stays anchored to the stellar background. Planetary positions are measured against the actual constellations rather than the moving equinox point.
The Gap — Ayanamsha§
The angular distance between the tropical starting point and the sidereal starting point is the ayanamsha. In 2026 it is approximately 23°–24°, depending on which scheme you use.
To convert a tropical longitude to sidereal: subtract the ayanamsha. If the Sun is at 15° Aquarius (tropical) and the ayanamsha is 23°30', the sidereal Sun is at 15° − 23°30' = 21°30' Capricorn. The Sun is one full sign earlier in the Vedic chart.
This is why every planet in a Vedic chart typically appears one sign earlier than in a Western chart. Not always exactly one sign — the ayanamsha of ~23–24° means planets near a sign boundary shift, while those near the middle of a tropical sign stay in the same Vedic sign at an earlier degree.
Why There Are Multiple Ayanamshas§
The sidereal zodiac's anchor point is defined relative to fixed stars — but which stars, and exactly where? Different scholars anchored the zero point to different stars or defined it through different methods, producing a family of ayanamsha values that disagree by 1–4 degrees.
| Ayanamsha | Definition | Approx. 2026 |
|---|---|---|
| True Citra default | 0° Aries = 180° from the star Spica (α Virginis). Uses the star's actual position — true longitude, not mean. | ~23°51' |
| Lahiri | The official Indian government standard. Based on Spica but uses mean position rather than true. Most widely used in India. | ~23°48' |
| Raman | B.V. Raman's personal system, anchored differently from Lahiri. | ~23°10' |
| KP | Krishnamurti Paddhati system. Close to Lahiri but slightly different. | ~23°47' |
| Yukteshwar | Sri Yukteshwar's system from The Holy Science. Smaller ayanamsha. | ~20°54' |
The differences are small — rarely more than 2–3 degrees between mainstream choices — but they can push border-degree planets into different signs, which materially changes a chart interpretation.
The Precession Rate§
The ayanamsha grows at approximately 50.3 arc-seconds per year. One complete cycle — the precession of the equinoxes — takes roughly 25,920 years. The ayanamsha was zero (the two zodiacs aligned) roughly 285 CE, depending on the scheme.
50" per year × 24 years ≈ 20' (0.33°) difference between charts cast in 2000 and 2024 using the same scheme. Negligible for most planets — but at a sign boundary, those 20 arcminutes can be decisive.
Moonketu Uses Sidereal Only§
All charts in Moonketu are calculated in the sidereal zodiac. The ayanamsha in use is shown in the status strip at the top of the chart tool and in the footer. You can switch ayanamshas from the settings drawer — the chart recalculates immediately.
The ayanamsha debate has never been fully resolved and probably cannot be, because the underlying question — what is the "correct" starting point for the zodiac — is partly observational, partly philosophical, and partly definitional. What matters practically is consistency: pick a scheme, apply it everywhere, and understand that your chart interpretation is always relative to that choice.