All planetary positions are calculated using Astronomy Engine, an open-source library created by Don Cross. This library is based on NASA's Jet Propulsion Laboratory (JPL) DE405/DE406 ephemeris data - the same data used by professional astronomers and space agencies worldwide for spacecraft navigation and astronomical research.
Precision & Accuracy
Planetary positions: Accurate to within 1 arcsecond (1/3600 of a degree)
Lunar positions: Accurate to within 3 arcseconds
Time range: 3000 BC to 3000 AD
This level of precision far exceeds what is needed for astrological purposes and matches professional astrology software like Solar Fire, Astro.com, and Time Passages.
Zodiac System: AstroPal uses the Tropical Zodiac (Western astrology), where 0° Aries aligns with the vernal equinox (around March 20-21 each year). This differs from the Sidereal system used in Vedic astrology.
Real-time Updates: Data refreshes every 60 seconds. All calculations happen entirely in your browser - no external API calls are made after the initial page load.