The sidereal zodiac measures signs from the stars. The tropical zodiac measures them from the March equinox. Daanyam uses the sidereal zodiac and the Lahiri ayanamsa, so a Vedic Sun, Moon, or Rising sign can differ from the sign in a Western app. That difference is the ayanamsa on the birth date.
Definition
Sidereal and tropical are two ways of naming the same sky. Tropical astrology ties 0° Aries to the March equinox. Sidereal astrology, including Jyotish, ties the signs to the stars. The angular gap between those zeros is the ayanamsa. Daanyam uses Lahiri, and that value changes with the date.
How it works
The tropical zodiac sets its starting point at the March equinox. The sidereal zodiac sets signs against the stars. The gap between those starting points is the ayanamsa.
Daanyam applies the Lahiri ayanamsa for the birth date. The worked example prints that date's value from the published engine golden. It is not a constant to subtract from every Western chart.
A Sun, Moon, or Lagna can therefore sit in the previous sidereal sign relative to a tropical app. The two results are different measurements, not two birth times.
Reference
What each zodiac is measuring
| Question | Daanyam |
|---|---|
| Zero point | Sidereal signs, using the Lahiri ayanamsa for the birth date. Not the March equinox. |
| What is computed | Sidereal Sun, Moon, Lagna, nakshatra, and Vimshottari. No tropical chart. |
| Sign names | Sanskrit rashi names, with the Western sign name only as a translation. |
| Timing | Dasha starts from the sidereal Moon's nakshatra, not from a tropical Sun sign. |
Worked example
One published birth shows the date-specific ayanamsa. The signs below are sidereal. They are not a claim about the tropical longitudes.
| Birth | Male, born 12 Aug 1995, 14:30 IST, Delhi |
|---|---|
| Date | 1995-08-12 |
| Time | 14:30 |
| Timezone | Asia/Kolkata |
| Lagna | Vrishchika (sidereal Scorpio) |
| Moon sign | Kumbha (sidereal Aquarius) |
| Moon nakshatra | Shatabhisha |
| Birth Mahadasha lord | Rahu |
| Lahiri ayanamsa | 23.798597° |
A common confusion
A different sign in a Western app is not evidence of a second birth time. The apps measure from different zero points. Daanyam does not convert its result into a tropical sign.
Calculate it
The Sun, Moon, and Rising calculator returns the sidereal Big Three. The Vedic birth chart page opens the free explainer for a longer reading.
How the numbers are computed
Lahiri, the ephemeris, and the list of things the engine does not compute are written up on the method page.
Questions
What is the difference between sidereal and tropical?
Tropical signs are measured from the March equinox. Sidereal signs are measured from the stars. Daanyam uses the sidereal zodiac with the Lahiri ayanamsa, so a Vedic sign can differ from the sign in a Western app.
Does Daanyam show my Western sign?
No. Daanyam computes sidereal positions only. A Western sign name appears on these pages as a translation of the rashi, not as a tropical longitude.
Is the ayanamsa a fixed number of degrees?
No. Lahiri ayanamsa depends on the date. The worked example prints the value from Daanyam's published engine golden for that birth. It is not a number to subtract from every tropical chart.