Jagannatha Hora (JHora) by P.V.R. Narasimha Rao is a landmark: a deep, free Windows application that serious students of Jyotish have relied on for decades. Its limitations are practical, not astrological — it runs on Windows, and its outputs assume you already know how to read them.
Science of Light aims at the same standard of accuracy in the browser: planetary positions and the ascendant validated against the Swiss Ephemeris to the arc-minute, Lahiri (or Raman/KP) ayanamsa, Vimshottari and additional dashas, divisional charts through D60, shadbala, ashtakavarga, KP with true Placidus cusps — on any device, phone included, with nothing to install.
The difference in intent: JHora is an instrument for people who read charts; Science of Light is that instrument plus the reading — every table has a plain-English interpretation path, and a practitioner Pro mode keeps the classical depth with source citations, so you can check its work.
Both compute from Swiss-Ephemeris-grade astronomy with the Lahiri ayanamsa by default, so planetary positions and dashas agree to within an arc-minute. Where conventions can differ (house systems, ayanamsa variants), the app labels its choices on the methodology page.
Yes — no account, no ads, computed on your device. The methodology and accuracy validation are public.
Free · no account · computed on your device to ±0.3′ vs the Swiss Ephemeris · methodology