A natal chart — also called a birth chart — is a map of the sky at the exact moment and place you were born. Not "your sign": your sign is one point on that map, the position of the Sun. The chart holds ten bodies, twelve houses, and the angles between them, and astrology reads the whole configuration rather than any single piece.
What a chart is made of
Planets. Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. In symbolic terms each stands for a function: the Sun for identity and direction, the Moon for emotional weather and need, Mercury for how you think and speak, Venus for what you value and how you attach, Mars for drive and anger.
Signs. The twelve 30° slices of the zodiac. A planet's sign describes the style in which that function operates — Mars in Libra pursues differently than Mars in Aries.
Houses. Twelve areas of life, derived from the horizon and meridian at your birth moment. Houses answer where: work, home, partnership, the body, other people's money. Houses depend on birth time; without it they cannot be placed reliably.
Aspects. The angular relationships between planets — conjunction (0°), sextile (60°), square (90°), trine (120°), opposition (180°). Aspects are where the tension and the ease actually live. A chart with many squares reads very differently from one dominated by trines.
The angles. The Ascendant (the sign rising on the eastern horizon at your birth), the Midheaven, and their opposites. The Ascendant is the classic "how you come across" point — and, like the houses, it needs a birth time.
Why birth time matters
The Moon moves roughly 13° a day and the Ascendant changes sign about every two hours. A four-hour error can move your Ascendant a whole sign and rotate every house placement in the chart. Duetto accepts a chart without a time and tells you plainly which parts of the reading are affected: the planets by sign and their aspects stay valid, the houses and the Ascendant do not.
If you do not know your time, a birth certificate is the usual source; in some countries hospital records or a national registry hold it.
How Duetto computes yours
- Your birth city is resolved to coordinates and to the time zone in force on that date — not today's offset, which is what makes pre-reform births go wrong in cheaper tools.
- Planetary positions are computed with the Swiss Ephemeris, the standard high-precision ephemeris used by professional astrology software.
- Our engine derives the houses, the angles, and the aspect grid with the orbs conventional for natal work.
- An AI language model reads that specific structure and writes it up in your language — starting from the strongest configurations, not from a template.
The astronomy is deterministic: the same birth data always yields the same chart. Only the wording of the interpretation varies.
How to read yours without drowning
Start with three things and ignore the rest until they make sense:
- Sun, Moon, Ascendant. Identity, inner life, and the face you lead with. Most of what people recognise as "themselves" sits in the interplay between these three.
- The tightest aspects. The closer the angle is to exact, the louder that pairing runs in your life.
- Stelliums and empty stretches. Three or more planets in one sign or house tells you where your attention concentrates.
A chart is not a verdict. It is a vocabulary for patterns you already live with — useful precisely when it names something you recognise but had not put words to.
Next steps
Natal readings in Duetto are free. Once you have yours, the chart becomes the base layer for everything else: daily transits show what today's sky touches in it, synastry reads it against someone else's chart, and the composite chart turns the two of you into a third chart of its own.
Duetto is for entertainment and reflection, not professional advice.