How this is calculated
Last updated 22 September 2026.
A Vedic birth chart is a map of where the sun, moon and planets were, from where you were born, at the moment you were born. Everything in your MoonMapped reading traces back to that one calculation. Here is what goes into it, and how it becomes the words you read.
The building blocks of your chart
Ascendant (Lagna). The zodiac sign rising on the eastern horizon at your exact time and place of birth. It sets the entire layout of your chart (which house every other sign and planet falls into), which is why an accurate birth time matters so much.
Moon sign (Rashi). The sign the Moon occupied at your birth. In Vedic astrology the Moon sign carries particular weight for temperament and mind: it is often the first thing a Vedic astrologer asks for.
Nakshatra. The zodiac is also divided into 27 lunar mansions, or nakshatras, each with its own character. Your Moon's nakshatra (and its quarter, or pada) adds a layer of detail beyond the sign alone.
Whole-sign houses. Vedic astrology divides your chart into twelve houses, each representing a life domain (self, wealth, home, career, and so on). MoonMapped uses the whole-sign house system (a well-established classical approach) where your ascendant’s entire sign is the first house, and each following sign is the next house in order.
Vimshottari dasha. A traditional Vedic timing system that divides your life into planetary periods (Mahadasha) and sub-periods (Antardasha), each ruled by a planet. Your current Mahadasha/Antardasha is the “chapter” your free reading tells you you're in.
Sidereal, with the Lahiri ayanamsa
Vedic astrology uses the sidereal zodiac, which is anchored to the actual, observable positions of the constellations. This is different from Western tropical astrology, which is anchored to the seasons. The difference between the two (roughly 24 degrees today) is called the ayanamsa. MoonMapped uses the Lahiri ayanamsa, the standard reference adopted by the Indian government and used by most traditional Vedic astrologers.
Three layers, three jobs
We deliberately keep three separate layers, so that no single component is doing more than one job:
- A deterministic engine computes your chart from your birth details: the ascendant, planetary positions, houses and dasha timeline described above. This calculation is astronomical: given the same birth details, it produces the same chart, every time.
- A rules layer maps the specific placements in your chart to established astrological interpretations, for example a rule about what a particular planet in a particular house tends to indicate. This layer decides what your chart means, before any AI is involved.
- AI takes the output of the rules layer and turns it into clear, readable prose. It is a writer, not an astrologer: it does not calculate positions, does not decide what a placement means, and does not invent dates or events that aren't in the underlying data.
Why this matters
Language models are good at writing sentences and bad at being consistently correct about facts. So we never ask the AI to be the source of truth about your chart or your dasha timeline: it only phrases what the deterministic engine and rules layer have already established. That is also why every insight in your reading shows the placement it came from: you can always trace a sentence back to the specific part of your chart that produced it, rather than taking it on faith.
See it for yourself
The clearest way to see how this works is to look at your own chart. Get a free reading to see it calculated for your own birth details.