Method and accuracy
How Astroo calculates your chart
Where the planet positions come from, how accurate they are, which zodiac and house system we use, and what the AI does and does not do.
Where the planet positions come from
Astroo calculates where the Sun, Moon and planets are for the exact moment you give it; it does not look them up in a table of interpretations. Positions are apparent positions as seen from Earth.
The same calculation drives the live 3D sky, the astrology calendar, the daily horoscopes and the transit screens, so the sky you see and the reading you get always agree.
How accurate it is
Planet positions are accurate to a tiny fraction of a degree, far finer than any aspect orb used in astrology.
Birth time matters much more. The Moon moves about half a degree an hour, and houses and the Ascendant turn through a full sign every two hours or so, so a birth time that is off by an hour can change them.
One moment, one chart
A chart is anchored to a single instant. Astroo converts the local birth time to UTC using the birthplace, then takes the planets and the houses from that same instant. Mixing a local clock time with a UTC calculation shifts the Moon by hours of motion and can change its sign, so reference charts are tested for it.
Zodiac, houses and points
Astroo uses the tropical zodiac, measured from the March equinox, which is the standard in Western astrology. It does not offer a sidereal zodiac. Houses on the birth chart are Placidus. Charts include the Ascendant and Midheaven, Chiron and the lunar nodes.
Aspects and orbs
An aspect counts when two bodies are within its orb of an exact angle. Astroo reads the five major aspects, with the same orbs for natal charts, transits and synastry. Every chart wheel draws exactly the aspects the written reading uses. The daily highlights use tighter orbs on purpose, so only the aspects worth reading about today are listed.
| Aspect | Angle | Orb |
|---|---|---|
| Conjunction | 0° | 8° |
| Sextile | 60° | 4° |
| Square | 90° | 6° |
| Trine | 120° | 6° |
| Opposition | 180° | 8° |
Transits, stations and eclipses
Sign changes, retrograde stations, moon phases and eclipses on the astrology calendar are calculated the same way, and the Life Timeline is tested against published dates for ingresses, stations, retrogrades and eclipses. Daily horoscopes are rebuilt every day at 00:45 UTC from the sky of that day. You can browse the raw positions in the daily planet positions table, which exports to CSV, or watch them in the live 3D sky.
What the AI does
The numbers are computed first. The AI astrologer then reads them through tools that fetch your natal chart, the current transits and your timeline, and explains what they mean in plain language. It is not asked to work out where a planet is. The astrology dictionary, which covers every planet in every sign and house, is written by Astroo.
Questions about the method
Where do Astroo's planet positions come from?
They are calculated, not looked up. Astroo works out where the Sun, Moon and planets are for the exact moment you give it, as they appear from Earth, and the same calculation drives the charts, the calendar, the horoscopes and the 3D sky.
How accurate are the charts?
Planet positions are accurate to a tiny fraction of a degree, far finer than any aspect orb. Birth time is the larger source of error: the Moon moves about half a degree an hour.
Which zodiac and house system does Astroo use?
The tropical zodiac, measured from the March equinox, which is the standard in Western astrology, and Placidus houses on the birth chart. Without a birth time the Life Timeline falls back to solar whole-sign houses, and the houses and Ascendant on a chart should not be trusted.
Does the AI calculate my chart?
No. The positions, houses and aspects are computed first. The AI astrologer then reads those numbers through tools that fetch your natal chart, current transits and timeline, and explains them in words. It is not asked to work out where a planet is.
Is astrology scientifically proven?
No. Astrology is a symbolic tradition, not a predictive science. Astroo calculates the sky exactly and offers interpretation to reflect on, not forecasts of events.