About Aurae
In short
Aurae is an astrology app. Your chart is calculated by code from where the planets actually were when you were born — tropical zodiac, Whole Sign houses. Readings are written by AI from that calculated chart, and this page says exactly where AI is and isn’t used.
What Aurae is
Aurae turns your birth date, time and place into a natal chart, then writes personal readings from it: daily horoscopes, tarot, compatibility and love timing. It also runs 22 free calculators that work without an account, and a library of articles on signs, placements, tarot and compatibility.
Aurae was founded by Vance Lim, whose byline appears on the library.
How charts are calculated
No part of the calculation uses AI. The same engine powers the calculators that take your birth details, your chart and the dates in your forecasts.
- Ephemeris
- Positions of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto come from astronomy-engine, an open-source astronomy library. They are geocentric — where each body appeared from Earth at your birth moment.
- Zodiac
- Tropical for the Western chart and calculators. Longitudes are measured from the equinox of date, which is the Western convention. The Vedic chart and calculators use the sidereal zodiac instead, with the Lahiri (Chitrapaksha) ayanamsa, as Jyotish does.
- Birth time
- Your local birth time is converted to Universal Time with your birthplace’s time-zone rules at that exact instant, so daylight-saving changes are handled.
- Rising sign
- The Ascendant is calculated from local sidereal time at your birthplace’s latitude and longitude (the standard formula in Jean Meeus’s Astronomical Algorithms). It moves through all twelve signs in about a day, so it needs an accurate birth time.
- Houses
- Whole Sign houses: the sign on your Ascendant is your 1st house, the next sign your 2nd, and so on around the zodiac. Aurae does not offer Placidus or other house systems.
- Nodes and Chiron
- The North Node is the mean node, with the South Node directly opposite. Chiron isn’t in astronomy-engine, so Aurae propagates its orbit from JPL Horizons orbital elements.
- Degrees
- Degrees are truncated, not rounded: a planet at 29.96° Libra shows as 29.9° Libra, never as a “30°” that doesn’t exist.
- Checked against a reference chart
- The engine is tested against a published chart with an AA Rodden rating (birth time from the birth certificate): Leonardo DiCaprio’s, from Astro-Databank. Sun and Moon agree within 0.03°, the Ascendant within 0.002°.
What two of the tools compute
- Compatibility calculator
- A Sun-sign score: element harmony, matching modalities, opposite signs and a traditional list of compatible signs. It is a first look, not synastry — it doesn’t use your birth charts.
- Love timing calculator
- Scans a year of Venus and Jupiter transits for supportive aspects to your natal Venus, Sun, Moon and the ruler of your 7th house, and for their passage through your 7th and 5th houses. A window scores higher when more of these indicators peak together.
How we use AI
- Not in the math. Positions, signs, houses, aspects and dates are computed by the engine above.
- In the readings. Personal readings — chart interpretations, daily horoscopes, tarot, compatibility readings and chat — are written by large language models: Anthropic’s Claude by default, with OpenAI’s models as an alternative provider. The model is given the placements and transits Aurae calculated for you and asked to interpret them; it doesn’t calculate anything itself.
- In the library. Articles in the Topics library were drafted with AI writing tools and are published under Vance Lim’s byline.
- What a reading is. Astrology is a symbolic tradition. Readings are for reflection — not medical, legal, financial or mental-health advice.
Found a mistake?
Email admin@auraeastrology.com with the page and what’s wrong. For more on the method, see how Aurae works.
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