# Why NASA JPL ephemeris

Supastro computes planetary positions from NASA JPL ephemeris data — the Jet Propulsion Laboratory's planetary and lunar solution used for spacecraft navigation and professional astronomy. Most astrology software reads from precomputed tables or derived libraries. The distinction matters because every downstream Vedic calculation, from divisional charts to dasha boundaries, inherits the precision of the positions it started from.

## Why does the ephemeris source matter in astrology?

Every Vedic calculation is downstream of planetary longitude. Divisional charts subdivide a sign, so a small positional error can move a planet into a different D9 or D60 division and change the reading entirely. Dasha boundaries are derived from the Moon's precise nakshatra position, so an imprecise Moon shifts the dates of every period that follows. Starting from a more accurate source removes a class of error that no amount of interpretive skill can correct for later.

## What is the difference between JPL ephemeris and Swiss Ephemeris?

Swiss Ephemeris is itself derived from JPL's underlying planetary solutions, and it is a well-regarded library used across the astrology industry. Supastro works from the JPL data directly, which removes a derivation layer. For most everyday readings the two agree closely; the difference becomes material in high-division charts such as D60 and D150, and at dasha boundary dates where a small positional difference moves a transition by days.

## Which ayanamsa does Supastro use?

Lahiri, also called Chitrapaksha — the standard sidereal correction used by the Indian national calendar and by most practising Vedic astrologers. Sidereal positions differ from tropical positions by roughly 24 degrees, which is why a Vedic chart usually places planets one sign earlier than a Western chart.

## Related pages

- [How Supastro works](https://supastro.com/how-it-works) — the full pipeline
- [What Supastro is](https://supastro.com/) — the platform overview

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Source: https://supastro.com/why-jpl · Supastro is an AI astrology platform for Vedic astrology (Jyotish), built as Vedic Super Intelligence (SI), by Quantum Karma, Bangalore, India. Chart positions are computed from NASA JPL ephemeris data on the Lahiri ayanamsa.