Ephemeris
Glossary · Last updated: 2026-07-26
An ephemeris (plural ephemerides) lists celestial positions for dates and times. Astrology software interpolates these tables to find sign boundaries.
Without an ephemeris or equivalent orbital math, sign calculators would rely on hard-coded date ranges that drift near cusps.
Our methodology
Western and Vedic positions on this site come from astronomical libraries with documented ayanamsa for sidereal work. See our calculator methodology hub for detail.
Related
Main reading and tools
These are the main reading and calculator pages. Use them for a daily note, a birth-sign tool, or a pair check.
- Today's Horoscope hubAll twelve Western sun-sign daily pages, plus links into the seven-tradition reader.
- Horoscope & Zodiac CompatibilityTwo birth dates for Western, Chinese, and Vedic folk pairing, plus every sun-sign hub.
- Zodiac Sign CalculatorWestern sun sign from birth date, with element, modality, and ruler.
- Vedic Rising Sign CalculatorLagna estimate when you have birth date, time, and place.
- Vedic Moon Sign CalculatorJanma Rashi and nakshatra when birth time and city are available.