Methodology

How Noviluna works

Some people think all of this is made up. It is the opposite: the positions of the stars are computed from astronomical ephemerides, what they mean comes from cited reference works, and the AI only writes. Here are the four steps, with their numbers, and how to check them yourself.

Today's sky, computed19 October 2026 · 12:00 UTC
Sun26°07′ ♎︎
Moon05°10′ ♒︎
Mercury19°38′ ♏︎
Venus03°31′ ♏︎retrograde
Mars12°06′ ♌︎
Jupiter22°38′ ♌︎
Saturn10°09′ ♈︎retrograde
Uranus05°05′ ♊︎retrograde
Neptune02°22′ ♈︎retrograde
Pluto03°04′ ♒︎

These figures are not typed by hand: they are computed when the page is generated. Compare them with any astronomical ephemeris.

See the full ephemeris

From your details to the answer, in four steps

  1. I

    Your details

    Date, time and place of birth. Your local time is converted to universal time using the time zone that applied in your town that day, daylight saving included. If you do not know the time, we do not invent an ascendant or houses: the chart comes without them, and we tell you so.

    to the minute
    how precisely we use your birth time
  2. II

    Exact positions

    An astronomical ephemeris engine computes where every body was —Sun, Moon, Mercury to Pluto, Chiron, the Lunar Nodes and Lilith— with their signs, houses (Placidus system) and aspects. It is calculation, not estimation: the same details always give the same result. The AI never computes or estimates a position.

    ≤ 3″
    difference from JPL Horizons (NASA) for the Sun and Moon
    13
    control charts, including births in the first minute of the Moon in a sign
  3. III

    A library of cited doctrine

    What each position, card and number means comes from a library curated from reference works, and every entry carries its source. We do not publish it in full, but we do say where it comes from.

    Where the doctrine comes from

    • PtolemyTetrabiblos2nd c. · planets, signs, houses and aspects
    • Alan LeoThe Progressed Horoscope1906 · progressions, with chapter and page
    • A. E. WaiteThe Pictorial Key to the Tarot1911 · the 78 cards and the spreads
    • Golden Dawn · A. CrowleyBook T · Liber 777c. 1888 · 1909 · tarot–astrology correspondences
    • Martin SchulmanKarmic Astrology, vol. 11975 · the Lunar Nodes
    • Melanie ReinhartChiron and the Healing Journey1989 · Chiron
    • Dane Rudhyar · Liz Greene · Robert HandModern psychological astrologyplanets, houses and transits; our own synthesis, none of their text copied
    • L. Dow Balliett · Florence CampbellPythagorean numerologythe life path number and the master numbers

    The public guides add Papus, Le Tarot divinatoire (1909), for the Tarot de Marseille, and Lenain, La Science cabalistique (1823), for the 72 angels.

    388
    doctrine entries, each with its source
  4. IV

    Selene writes, she does not invent

    Selene, the AI guide, receives your chart already computed and the doctrine that goes with it, and turns it into clear text for you. She cannot add positions or doctrine of her own. Before you read her reply, automatic checks compare it with your details; if something does not match, it is rewritten.

    What is checked before you read Selene

    Before she starts writing, two filters: one detects signs of crisis, the other questions about money, health or the law. Then her reply is compared with:

    1. 01the positions in your chart
    2. 02the houses
    3. 03the aspects
    4. 04each planet's sign today
    5. 05your age and cycles
    6. 06your life path number
    7. 07cards made up without a spread
    8. 08cards that were not drawn
    9. 09each card's orientation
    10. 10the language
    11. 11Spanish register (tú, never vos)
    12. 12internal jargon
    13. 13grammar and gender

    Read the AI transparency statement

    13
    automatic checks on her replies, before you read them
    437
    control questions in 10 languages, re-run every time we change Selene

What Selene never does

  • Compute or estimate a position: they all come from the ephemeris engine.
  • Invent doctrine, cards that were not drawn or your life path number.
  • Predict your health, a pregnancy, a death or an investment.
  • Decide a purchase, a signature, a treatment or a lawsuit for you.
  • Carry on with the reading in a crisis: she stops and points you to professional help.
  • Pretend to be a person: you always know you are talking to an AI.

Check it yourself

No need to take our word for it: everything that is computed can be checked.

  1. The sky on any day

    We publish where every planet is, in degrees and minutes. Compare any date with the astronomical ephemeris of your choice.

    Open the ephemeris

  2. Your chart, in another program

    Compute your chart for free and put it next to one from any serious astrology software: Sun, Moon and Ascendant must match.

    Compute my chart

  3. The source of every guide

    Every page on planets, signs, houses and tarot cards names the work its doctrine comes from.

    See the planets

Frequently asked questions

Does the AI make up the horoscope?

No. Positions are computed from astronomical ephemerides —the Sun and Moon land within 3″ of JPL Horizons (NASA) in our 13 control charts— and what they mean comes from 388 doctrine entries, each with its source. The AI only writes and personalises that material, and 13 automatic checks compare its replies with your details before you read them.

Where does the astrology and tarot doctrine come from?

From reference works: Ptolemy's Tetrabiblos for classical astrology, Alan Leo's The Progressed Horoscope (1906) for progressions, Waite (1911) for the Rider-Waite-Smith tarot and modern psychological astrology (Rudhyar, Greene, Hand), among others. Every entry carries its source.

How can I check the calculations are right?

Open our ephemeris for any day and compare the degrees with any astronomical source, or compute your chart for free and put it next to one from another astrology program.

Can I quote Noviluna's content?

Yes. The free content (sign horoscopes, retrograde guides, tarot cards) may be quoted with attribution to Noviluna and a link to noviluna.app.

Why does Noviluna refuse to answer some questions?

By design: it never makes predictions about health, pregnancy, death or investments, and when crisis signals appear it points to professional help. A filter spots those questions before Selene writes. Better not to advise than to advise badly.

Your sign's horoscope isn't really yours

Your personalized transit —calculated from your full birth chart, not just your sign— is far more precise.

Calculate my chart free ✦