How we calculate
Updated:
Every chart, compatibility score and forecast on Stellyra is computed from real astronomical data — not from generic sign templates. This page documents exactly how, so you can judge our work the way you would judge any source.
Planetary positions
Birth charts, transits and retrograde calendars use astronomical ephemeris calculations of the actual positions of the Sun, Moon and planets for the exact date, time and place you enter. We work in the tropical zodiac — the standard of Western astrology, anchored to the equinoxes.
- Sun, Moon, Mercury–Pluto: ecliptic longitude to the arc minute
- Retrograde status taken from real apparent motion, including stations and shadow periods
- Timezone and daylight saving resolved from your birth place and date
House system
We use Placidus houses — the most widely used system in Western astrology. The Ascendant and Midheaven come from your exact birth time and coordinates, which is why an accurate birth time matters: the Ascendant changes sign roughly every two hours.
Aspects and orbs
An aspect counts only when two planets are within the orb below. Tighter orbs weigh more in every interpretation and score.
| Aspect | Angle | Orb |
|---|---|---|
| Conjunction | 0° | 8° |
| Opposition | 180° | 8° |
| Trine | 120° | 8° |
| Square | 90° | 7° |
| Sextile | 60° | 6° |
| Quincunx | 150° | 3° |
Synastry scores
The synastry calculator compares two full charts planet by planet. Each aspect adds or subtracts points by its nature (trines and sextiles harmonious, squares and oppositions challenging) and its weight scales with how exact the aspect is — a 1° trine influences the score far more than a 7° one. Personal planets (Sun, Moon, Venus, Mars) weigh more than outer planets.
Sign compatibility scores
Sign-to-sign scores (the 1–10 ratings on our compatibility pages) are editorial ratings built from three classical factors: the elements of both signs (fire, earth, air, water), their modalities (cardinal, fixed, mutable) and the whole-sign aspect between them (sextile, square, trine, opposition). They describe the archetypal dynamic of two signs — a full synastry of two birth charts is always more precise.
Horoscopes and forecasts
Daily, weekly, monthly and yearly horoscopes start from the real transits of the period — which planets actually aspect each sign — and are written up by our editorial team. Articles are signed Stellyra Editorial; personal readings and forecasts name the practitioner who prepared them.
What astrology is — and is not
Astrology is a symbolic language of self-reflection with a millennia-long tradition, not a science that predicts events. We keep the astronomy exact and the interpretation honest: no fear-mongering, no medical or financial advice, no guaranteed outcomes. Sources are listed under every article, and we correct mistakes when readers point them out.
Frequently Asked Questions
Which zodiac do you use — tropical or sidereal?
Tropical, the standard of Western astrology. Signs are anchored to the equinoxes, so precession and the "13th sign" do not change your Sun sign.
Why does my Ascendant need an exact birth time?
The Ascendant moves through all 12 signs every day, changing sign roughly every two hours. An error of 30 minutes can shift your Ascendant and every house cusp.
Why do different sites give different compatibility scores?
Sign-level scores are editorial by nature — they depend on how each site weighs elements, modalities and aspects. We publish our exact criteria on this page; most sites publish none.
Are your horoscopes written individually for each sign?
Yes. Each period we compute the real transits affecting every sign and our editorial team writes twelve separate texts from them — no recycled templates.