Methodology
How Danu calculates your chart.
Every position, orb and rule Danu uses, with a published chart you can check against any ephemeris. The math is exact; the interpretation is Danu's.
The engine
Three choices, and why
Swiss Ephemeris
Planetary positions come from the Swiss Ephemeris, the high-precision engine derived from NASA JPL’s planetary ephemerides, with its data files for roughly the years 1200 to 2400. Positions are geocentric, as seen from Earth, and given to the minute of arc. The lunar node is the true node; Lilith is the mean lunar apogee.
Tropical zodiac
Signs are measured from the March equinox, so they follow the seasons rather than the constellations behind them. It’s the standard in Western astrology.
Whole Sign houses
The sign rising at your birth is your whole 1st house, the next sign your 2nd, and so on. It’s the oldest house system and the clearest: no house is ever split between signs.
Your birth time is converted to Universal Time with the IANA time zone database and its record of past offsets and daylight saving changes.
The dated sky pages (new and full Moons, eclipses, retrogrades and the monthly calendar) are computed separately with astronomy-engine, an open-source ephemeris accurate to about a minute of arc, and shown in universal time.
Check it yourself
A published chart
Carl Sagan, born November 9, 1934 at 17:05 in Brooklyn, NY, USA. Rodden rating AA: the time comes from the birth record.
| Point | Position | House |
|---|---|---|
| Ascendant | 25°22′ Taurus | 1 |
| Midheaven | 3°23′ Aquarius | — |
| 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 |
| Jupiter | 6°28′ Scorpio | 7 |
| Saturn | 21°40′ Aquarius | 10 |
| Uranus | 28°45′ Aries ℞ retrograde | 12 |
| Neptune | 14°11′ Virgo | 5 |
| Pluto | 26°03′ Cancer ℞ retrograde | 3 |
| North Node | 4°16′ Aquarius ℞ retrograde | 10 |
| Chiron | 8°23′ Gemini ℞ retrograde | 2 |
To check it, enter the same birth data in any Swiss Ephemeris–based calculator with the tropical zodiac and Whole Sign houses: November 9, 1934, 17:05 Eastern Standard Time (22:05 UT), latitude 40.6782°, longitude 73.9442° W. Positions here are cut to the minute of arc, so expect agreement to within a minute or two.
Aspects and orbs
Every orb Danu uses
An orb is how far from exact an aspect can be and still count. Danu uses different orbs for different jobs, because a birth chart, a passing transit and two charts side by side are different questions.
Aspects in your birth chart
Each surface uses its own set: conversation stays tight, written readings allow a little more, and the wheel draws a few extra lines.
| Aspect | Conversation | Written readings | Chart wheel |
|---|---|---|---|
| Conjunction (0°) | 6° | 8° | 8° |
| Opposition (180°) | 6° | 8° | 7° |
| Trine (120°) | 5° | 7° | 6° |
| Square (90°) | 5° | 7° | 6° |
| Sextile (60°) | 4° | 5° | 4° |
Written readings are your natal introduction, Premium reports and Portraits.
Transits
Set by the moving planet, for every aspect it makes.
| Sun | 1.5° |
|---|---|
| Moon | 2° |
| Mercury | 1.5° |
| Venus | 1.5° |
| Mars | 2° |
| Jupiter | 2.5° |
| Saturn | 3° |
| Uranus | 3° |
| Neptune | 3° |
| Pluto | 3° |
| North Node | 1.5° |
| Chiron | 2° |
| Lilith | 1° |
Two charts (synastry)
Base orb, before the per-planet factor below.
| Conjunction (0°) | 8° |
|---|---|
| Sextile (60°) | 6° |
| Square (90°) | 8° |
| Trine (120°) | 8° |
| Opposition (180°) | 8° |
| Semi-sextile (30°) | 2° |
| Semi-square (45°) | 2° |
| Quincunx (150°) | 3° |
| Sesquiquadrate (135°) | 2° |
In synastry the base orb is scaled by the tighter of the two planets: luminaries (Sun, Moon) ×1, personal and social (Mercury, Venus, Mars, Jupiter, Saturn) ×0.75, outer (Uranus, Neptune, Pluto) ×0.6, points (North Node, Chiron, Lilith) ×0.4. Transits use the same nine aspects as synastry, each within the moving planet’s cap. The transiting Moon is left out of the daily transit list by default: it moves so fast that it aspects something almost every hour.
A transit is applying when it’s getting tighter and separating when it’s loosening: Danu compares the orb now with the orb 24 hours later. Because planets appear to turn retrograde, a slow planet can cross the same point of your chart up to three times, which is why a transit can seem to come back.
No birth time?
Danu leaves out what it can’t know
Without a time, Danu computes your chart for noon as a placeholder and marks it time-unknown. Your planets’ signs and the aspects between them barely change over a day, so they stay. Your chart never shows a rising sign, Midheaven or houses, and the daily transit views drop transits to them.
The Moon moves about 13° a day, so its degree is uncertain too. Written readings leave the Moon out entirely. In conversation, Danu is told your time is unknown and instructed never to state a rising sign or house as fact. When you add your time, the missing pieces appear.
Famous charts
Only verified birth data
Every famous chart carries its Rodden rating from Astro-Databank, the standard grade for how reliable a birth time is. AA means a birth certificate or birth record, A a quoted source such as the person or their family, B a biography.
Charts rated AA, A or B are read in full, houses and rising sign included. A chart with a verified birth date and place but no reliable time is shown by sign only, and any of the faster planets (the Sun, Moon, Mercury, Venus and Mars) that changed sign that day is left out. Charts with unverified or conflicting times (C and DD) aren’t published, and every chart is reviewed before it goes live.
Where AI fits
Facts first, writing second
Your chart and transits are computed by code, not by a language model. The model reads those facts and writes from them; it never calculates a position.
Readings written ahead of time, like your natal introduction, reports, weekly synthesis and Portraits, are scored by a second model acting as a judge before you see them, and several are first checked by code for any placement your chart doesn’t have. A draft that fails is rewritten or held back. Live conversation is written in the moment, from the same computed facts.
Danu’s rules forbid predicting events as certain, diagnosing, or giving medical, legal or financial advice. Transits are pressure and possibility; what you do with them is yours. When the chart can’t answer something, Danu says so.
Connect my worst career setback to my transits and tell me when this current heavy chapter actually wraps up.
The chart doesn't tell me which setback — and I won't guess. But I can tell you what structural signature would produce a major career blow for you, and map the current chapter against it.
Saturn has been grinding through your 3rd house in Aries, squaring your natal Neptune — whatever avoidance propped up your professional identity has been getting stripped. That's the heavy chapter.
Saturn doesn't clear your 3rd house until it crosses into Taurus, around mid-2027. You have roughly 12–13 more months of this particular pressure.
Saved
Glossary
The terms, defined
- Tropical zodiac
- The zodiac measured from the March equinox, so 0° Aries is where the Sun sits on the first day of spring in the Northern Hemisphere. Signs follow the seasons, not the constellations behind them.
- Whole Sign houses
- The house system where the whole sign rising at birth is the 1st house, the next sign is the 2nd, and so on. Each house is exactly one sign.
- Ascendant (rising sign)
- The degree of the zodiac rising on the eastern horizon at the moment and place of birth. It needs an exact birth time: it moves about a degree every four minutes.
- Midheaven
- The degree of the zodiac at the top of the sky at birth. Like the Ascendant, it needs an exact birth time.
- Aspect
- A meaningful angle between two points in a chart: conjunction (0°), sextile (60°), square (90°), trine (120°) and opposition (180°), plus minor angles.
- Orb
- How far from exact an aspect can be and still count. A square with a 2° orb is 88° or 92° apart.
- Applying and separating
- Whether an aspect is getting tighter (applying) or looser (separating). Danu compares the orb now with the orb 24 hours later.
- Transit
- A planet's current position in the sky, read against your birth chart.
- Retrograde
- A planet's apparent backward motion as seen from Earth. It's why a slow planet can cross the same point of your chart up to three times.
- Synastry
- Reading two birth charts against each other: the aspects between one person's planets and the other's, and where each person's planets fall in the other's houses.
- Decan
- A ten-degree third of a sign. Each sign has three.
- Rodden rating
- A grade for the reliability of a birth time, from Astro-Databank. AA is a birth certificate or birth record; A is a quoted source such as the person or family; B is a biography; C, DD and X mean an unverified, conflicting or missing time.
Run it on your own chart.
See what it’s saying — then keep Danu in your pocket.