Local astronomy engine
Planetary positions are calculated on the application server with MIT-licensed Astronomy Engine. The chart uses tropical, geocentric longitudes; Earth is not presented as a natal planet. Lunar nodes are true/osculating nodes. Birth details are not sent to an external astrology or AI service to generate readings.
Time and location
Local birth time is converted to UTC using historical rules from the selected IANA time zone. Latitude and longitude come from GeoNames city data; manual coordinates are available for smaller places. The ascendant, MC and chosen house system are calculated from this location and time.
Precision and comparison
Astronomy Engine targets approximately one arcminute of precision. Starmora compares sample planetary and angle calculations against independent reference results. These checks do not guarantee zero difference for every date. Placements near sign or house boundaries and approximate birth times require particular care; calculation notes are shown in the chart and report.
Sources and approach
These sources explain the page's traditional concepts or calculation context. Original Starmora examples and reflection prompts are not predictions attributed to the sources.