Western Natal Birth Chart (西洋本命星盤)

The Whole Birth Chart — Every Planet, House, Angle and Aspect

Overview

The natal birth chart is the foundation of all Western astrology — the snapshot of the sky at the exact moment and place you were born, from which every other technique (progressions, solar returns, transits, synastry) is derived. askTIAN's natal chart is the complete article: all ten planets placed in their zodiac signs AND their houses, the four angles (Ascendant, Midheaven, Descendant, Imum Coeli), the full grid of Ptolemaic aspects between the planets, each planet's essential dignity and retrograde state, the chart ruler, the lunar phase, and the balance of elements, modalities and hemispheres. It is the chart an astrologer reads first, returned as clean structured data.

Origin & history

The horoscopic natal chart — a wheel of twelve houses rising from the eastern horizon, with the planets placed by sign and house — took its mature form in the Hellenistic world around the 1st century BCE, synthesising Babylonian planetary omens, Egyptian decans and Greek geometry. Claudius Ptolemy's 'Tetrabiblos' (2nd century CE) systematised the aspects — conjunction, sextile, square, trine and opposition — that still structure chart reading today. The tropical zodiac (measured from the March equinox) and the system of essential dignities (a planet's strength by sign) descend directly from this tradition.

For two millennia the natal chart has been the beating heart of Western astrology, surviving the shift from an earth-centred cosmos to a heliocentric one by remaining explicitly geocentric and symbolic — it maps the sky as seen from a place on Earth, not the physics of the solar system. The house systems multiplied over the centuries (Placidus, the most common today, divides each quadrant by time; Whole-Sign, the oldest, gives each sign a whole house; Equal houses space them 30° from the Ascendant), and modern astrology added the three outer planets Uranus, Neptune and Pluto after their telescopic discovery. askTIAN computes positions on the same Meeus ephemeris the rest of its Western engine is gold-locked against — the Sun and Moon reproduce Albert Einstein's documented chart to the arcminute.

How it works

Provide birth date, birth time and birthplace (latitude, longitude and the UTC offset in force at birth — houses and angles require an exact time and place). The engine computes the ten planets' tropical longitudes and the Ascendant/Midheaven on the shared ephemeris, builds the twelve house cusps in your chosen system (Placidus by default, or Whole-Sign / Equal), and places each planet in its house. It then measures every planet-to-planet angle against the five Ptolemaic aspects (with the Sun and Moon granted a wider orb), flags each aspect as applying or separating, assigns each planet its essential dignity (domicile, exaltation, detriment, fall or peregrine) and retrograde state, identifies the chart ruler and lunar phase, and tallies the fire/earth/air/water, cardinal/fixed/mutable, and hemisphere/quadrant distributions.

Good for

Use cases

Full Natal Reading

Send birth date, time and place and receive the whole chart — ten planets in signs and houses, four angles, the aspect grid, dignities, chart ruler, lunar phase and the elemental/modal balance.

Choose Your House System

Request Placidus (the modern default), Whole-Sign (the oldest, one sign per house) or Equal houses — the same planets, cast into whichever framework you read in.

The Aspect Grid

Get every Ptolemaic aspect between the planets and angles, each with its exact orb and whether it is applying (tightening) or separating — the relationships that shape the chart's story.

Chart Signature

Read the balance of fire/earth/air/water and cardinal/fixed/mutable, the hemisphere emphasis, the chart ruler and the Moon's phase — the quick 'signature' an astrologer sizes up first.

Key terms

Ascendant (Rising Sign)
The zodiac degree rising on the eastern horizon at birth — the cusp of the 1st house and the chart's most time-sensitive point, describing the outward self and the 'lens' on the whole chart.
House
One of twelve divisions of the local sky, each governing an area of life (self, resources, communication, home, …). A planet's house says WHERE in life its energy plays out; askTIAN offers Placidus, Whole-Sign and Equal.
Aspect
A significant angular relationship between two planets — conjunction (0°), sextile (60°), square (90°), trine (120°) or opposition (180°) — within an orb. Applying aspects are tightening toward exact; separating ones are pulling apart.
Essential Dignity
A planet's strength by sign: domicile (its own sign), exaltation (its sign of honour), detriment (opposite domicile), fall (opposite exaltation) or peregrine (none) — the classical measure of how well-placed it is.
Midheaven (MC)
The zodiac degree culminating at the top of the chart — the cusp of the 10th house, marking career, public standing and life direction; with the Ascendant it fixes the chart's frame.

API

The askTIAN Natal Birth Chart endpoint takes birth date, time and place and returns the complete tropical, geocentric chart: all ten planets in their signs and houses (with retrograde flags and essential dignities), the four angles (Ascendant with its ruler, Midheaven, Descendant, Imum Coeli), the full Ptolemaic aspect grid (each aspect with its orb and applying/separating state), the chart ruler, the lunar phase, and the elemental / modal / polarity / hemisphere / quadrant distributions. Choose Placidus (default), Whole-Sign or Equal houses. Positions come from the same Meeus ephemeris the rest of the Western engine is gold-locked against — the Sun and Moon match Einstein's documented chart to the arcminute. A best-effort LLM reading is returned in parsable sections (set interpretation:false for structured data only). Honest rails: a symbolic language for reflection, not a predictive science, and not medical, legal or financial advice.

Endpoint: POST /trpc/astrology.natalChart — 1 TIAN Points. See the API documentation and Playground.