How Danu works
Calculated by code. Explained by AI. Answerable to a person.
Danu takes astrology seriously enough to calculate all of it. Here is exactly what happens between your birth details and a reading, including the parts that aren’t finished yet.
By Kenton Tilford, founder
Step 1
Your birth details
Date, time and place become one moment.
Your birthplace becomes coordinates and a time zone. Danu converts your birth time to Universal Time using the IANA time zone database, which records every past offset and daylight saving change, so a birth time from decades ago means what it meant then. Before a region adopted standard time, the time is read as local mean time.
No birth time? Danu computes your chart for noon as a placeholder and leaves out what it can’t know: your rising sign, Midheaven, houses, and transits to them.
Step 2
Your chart, calculated
The Swiss Ephemeris, to the minute of arc.
Positions come from the Swiss Ephemeris, which is derived from NASA JPL’s planetary ephemerides. Danu uses the tropical zodiac, Whole Sign houses, the true lunar node and the mean Lilith, across thirteen bodies and points plus your Ascendant and Midheaven. A language model never calculates a position.
| Point | Position | House |
|---|---|---|
| Ascendant | 25°22′ Taurus | 1 |
| Sun | 16°50′ Scorpio | 7 |
| Moon | 21°52′ Sagittarius | 8 |
| Mercury | 3°28′ Scorpio ℞ retrograde | 7 |
| Venus | 14°34′ Scorpio | 7 |
| Mars | 13°09′ Virgo | 5 |
Step 3
The relationships inside it
Aspects, each with a published orb.
An aspect is an angle between two points in your chart; an orb is how far from exact it can be and still count. Danu publishes every orb it uses, and the published numbers are tested against the code.
Carl Sagan’s tightest aspects, calculated
- Moon sextile Saturnorb 0°12′
- Venus sextile Neptuneorb 0°23′
- Mars conjunction Neptuneorb 1°02′
- Venus sextile Marsorb 1°25′
- Sun conjunction Venusorb 2°16′
Calculated from the published positions above, which are cut to the minute of arc, so an orb can differ by a minute or two from other software.
Step 4
The sky against it
Today’s transits, by degree.
Every day Danu computes where the planets are and the aspects they make to your chart. How wide an orb counts depends on the moving planet: tighter for fast planets, wider for slow ones. A transit is applying while it tightens and separating as it loosens.
The Moon is left out of the daily list: it moves so fast that it touches something in your chart almost every hour.
Step 5
What matters, decided by rules
| Group | Transit | Why |
|---|---|---|
| First | Saturn, Uranus, Neptune or Pluto, touching anything in your chart | Slow planets; these shape weeks and months |
| Second | Jupiter, touching anything in your chart | Slower than the personal planets, faster than the outer ones |
| Third | The Sun, Mercury, Venus or Mars, touching your Sun, Moon, rising sign or Midheaven | Fast, so only contacts to the most personal points count |
Within a group, the tightest orb leads. That rule decides the first line of your day and the order of the evidence under it. Everything else is still calculated, but kept out of your daily reading. Danu sends a notification only when a slow planet is within half a degree of your Sun, Moon, rising sign or Midheaven and still tightening.
Code makes these choices, not the AI.
Step 6
The reading, written by AI
Anthropic’s Claude writes from the facts it’s handed.
Only now does an AI model enter. Danu gives it your calculated chart, today’s ranked transits and the context you’ve chosen to share, inside rules people wrote. The rules forbid predicting events as certain, telling you your fate, diagnosing, giving medical, legal or financial advice, inventing a famous person’s chart, and mixing house systems. If you say you might be in danger, Danu stops reading the chart and points you to real help.
Checked before you see it
Written readings (your natal introduction, Premium reports and Portraits) are checked by code for any placement your chart doesn’t have, and scored by a second model. A draft that fails is rewritten or held back. Every Portrait is also reviewed by a person.
Not second-checked yet
Live conversation and the free daily reading are written in the moment from the same calculated facts, but they don’t get that second check yet. We’d rather tell you than let you assume.
Step 7
Shown to you
“Why this?”
Under your daily reading, “Why this?” opens the exact contacts behind it: the transit, the point it touches in your chart, the orb to the minute, and whether it’s tightening. You’ll find the same kind of evidence on your chart, on your Circle and Couple pages, in Premium reports (“Based on”) and in Portraits (“Chart grounding”).
The math is exact. The interpretation is Danu’s, and she shows you where it came from.
Step 8
The people
What stays human.
- The method: the ephemeris, the zodiac, the house system, every orb and the ranking.
- The rules the AI has to follow, and the safety boundaries.
- Danu’s voice, and what she will and won’t say.
- What ships, and what doesn’t.
I’m Kenton Tilford. I built Danu, and I answer for what she says. If she gets something wrong, I want to know: hello@danuastrology.com.
Step 9
Privacy
Your chart is yours.
- No ads, and your data is never sold or shared for advertising.
- Your conversations aren’t used to train AI models.
- The companies that process data for Danu are named in the privacy policy, including Anthropic, which writes readings, and OpenAI, which powers memory search.
- Delete your account and everything goes, within minutes.
Step 10
Getting better
Published, versioned, and checked before it ships.
New kinds of reading are scored against quality thresholds before they’re switched on. The method is published, and when it changes, this page and the methodology page change with it. The date at the top says when.
Questions
The honest answers
Does ChatGPT just make up my horoscope?
No. Danu calculates your chart and today's transits in code with the Swiss Ephemeris; the AI never calculates a position. Fixed rules, not the AI, decide which transit matters most. Then an AI model (Anthropic's Claude) writes the reading from those facts, inside rules people wrote: no fate, no certain predictions, no medical, legal or financial advice, no invented famous charts. Danu shows you the placements behind the reading, so you can check her.
Is Danu a person?
No. Danu is an AI astrologer. She'll tell you so if you ask, and she never pretends to be human. The person responsible for her is Kenton Tilford, Danu's founder.
Who writes the rules Danu follows?
People. Danu's founder, Kenton Tilford, sets the method (the Swiss Ephemeris, the tropical zodiac, Whole Sign houses, the orbs and the ranking), the rules the AI must follow, Danu's voice and her safety boundaries. The method and its numbers are published on the methodology page.
Does Danu predict the future?
No. Danu tells you what the sky is doing to your chart, when, and what that tends to mean. She doesn't predict events, and she never tells you your fate.
What happens to my data?
Your birth data and conversations are saved to your account so Danu can keep reading your chart. They're never sold or used for advertising, and never used to train AI models. You can download or delete everything from your account page.
See it on your own chart.
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