Sidereal vs tropical: why your Vedic sign is different
Vedic astrology (Jyotish) uses the sidereal zodiac, measured against the fixed stars; Western astrology uses the tropical zodiac, anchored to the March equinox. Because of the Earth's axial precession the two frames drift apart by about one degree every 71.6 years, and today the difference — the ayanamsha — is exactly 24°13′49″ (Lahiri, computed by our engine for today). That is why a "Taurus Sun" in a Western chart is very often a Mesha (Aries) Sun in a kundli: most positions shift back by almost one full sign.
Ayanamsha (Lahiri) today: 24°13′49″ · Swiss Ephemeris
Around 285 CE the two zodiacs coincided. The Earth's axis traces a slow cone — the precession of the equinoxes — completing a circle in roughly 25,800 years, so the equinox point slides backward through the constellations at about 50.3″ per year. The tropical zodiac follows that moving point; the sidereal zodiac stays with the stars. The gap between them is the ayanamsha, and in the Lahiri reckoning used by official Indian panchangs it is 24°13′49″ today.
Jyotish kept the stellar frame because its core toolkit is stellar: the 27 nakshatras are actual star groups, and the dasha clock starts from the Moon's position inside a real nakshatra. A zodiac that drifts from the stars would detach the rashis from the nakshatras they contain — so the sidereal choice is structural, not a preference.
| Sign | Tropical (Western) | Sidereal (Jyotish, 2026) |
|---|---|---|
| मेष Meṣa (Aries) | Mar 21 – Apr 19 | 14 Apr – 15 May |
| वृषभ Vṛṣabha (Taurus) | Apr 20 – May 20 | 15 May – 15 Jun |
| मिथुन Mithuna (Gemini) | May 21 – Jun 20 | 15 Jun – 16 Jul |
| कर्क Karka (Cancer) | Jun 21 – Jul 22 | 16 Jul – 17 Aug |
| सिंह Siṃha (Leo) | Jul 23 – Aug 22 | 17 Aug – 17 Sept |
| कन्या Kanyā (Virgo) | Aug 23 – Sep 22 | 17 Sept – 17 Oct |
| तुला Tulā (Libra) | Sep 23 – Oct 22 | 17 Oct – 16 Nov |
| वृश्चिक Vṛścika (Scorpio) | Oct 23 – Nov 21 | 16 Nov – 16 Dec |
| धनु Dhanu (Sagittarius) | Nov 22 – Dec 21 | 16 Dec – 14 Jan |
| मकर Makara (Capricorn) | Dec 22 – Jan 19 | 14 Jan – 13 Feb |
| कुम्भ Kumbha (Aquarius) | Jan 20 – Feb 18 | 13 Feb – 15 Mar |
| मीन Mīna (Pisces) | Feb 19 – Mar 20 | 15 Mar – 14 Apr |
Sidereal dates are the real sankranti-to-sankranti spans for 2026, computed with the Swiss Ephemeris (Lahiri ayanamsha) in IST — they shift by a day across years. Tropical dates are the familiar Western ranges.
The full story of the ayanamsha — and why Lahiri is the standard — is here: Lahiri ayanamsha →
- Why is my Vedic sign different from my Western sign?
- Because the two systems measure from different starting points. The Western tropical zodiac starts at the equinox; the Vedic sidereal zodiac starts at a fixed point among the stars. They currently differ by 24°13′49″, so roughly four out of five people have a Sun sign one sign earlier in Jyotish than in Western astrology.
- Which zodiac is "more accurate" — sidereal or tropical?
- Neither is astronomically wrong: they are different reference frames, both computed from the same ephemeris. Sidereal positions match where planets stand against the actual stars; tropical positions track the seasons. Jyotish is built on the sidereal frame because its nakshatras and dashas depend on real star positions. Which framework of interpretation you trust is a separate — and personal — question.
- What is the exact difference between the zodiacs right now?
- 24°13′49″ (Lahiri ayanamsha), growing by about 50.3 arc-seconds per year. This page recomputes the value daily with the Swiss Ephemeris.
- Does the "13th sign" (Ophiuchus) change Vedic astrology?
- No. The 12 rashis are equal 30° divisions of the ecliptic, not the unequal constellations that share their names. The Sun does pass through the constellation Ophiuchus, but zodiac signs — sidereal and tropical alike — are a coordinate system, so no sign is added or removed.