Astrology Vocabulary, Bottom Up

A working glossary for building an astrology app. Terms come from the feature matrix in the order the domain is built — sky and clock, zodiac, signs and houses, bodies, aspects, chart types, the Vedic stack, delivery — so no term appears before its prerequisite.

Conventions used throughout

• Longitude is one number, 0–360°, measured eastward along the ecliptic. 0° is the tropical vernal equinox; the sidereal zero point differs (see Ayanamsa).
• Humans read <sign> <degrees>′; JSON stores decimal degrees (5°12′ → 5.2).
• Timestamps are UTC in storage; the birth time zone is kept for display.
• “Western” means the tropical/Hellenistic tradition; “Vedic” means sidereal Jyotish.

How to use this guide

Read layers 0–2 for the coordinate basics, then jump to a term when a design links here. The examples illustrate domain concepts; the JSON sketches are not the implemented adapter contract. For current package boundaries, read the binder architecture.

Binder and architecture terms

See routing, normalization, semantics and comparison for the package responsibilities.

The layer map

Layer 0 — The sky and the clock

Every chart value is a body’s position at an instant, computed from an ephemeris. If this layer is wrong, everything above it is wrong.

Ephemeris

A table or computational model giving body positions over time. A provider evaluates its model at a requested instant; an adapter translates the answer into the application’s contract. The Swiss adapter computes locally, while the NASA adapter queries Horizons over HTTP.

Julian Day (JD)

A continuous day count used by ephemerides, with a day boundary at noon. Its conventional epoch is noon on 1 January 4713 BCE in the Julian calendar. Always name the time scale: the same instant has different numerical Julian Days in UT and TT. Converting a civil time still requires resolving its timezone and calendar first.

Time scales: UTC, UT, TT and Delta-T

UTC is the civil reference used by absolute input timestamps. UT relates to Earth’s rotation; TT is a uniform time scale used for dynamical calculations. Delta-T is TT minus UT, in seconds. They cannot be substituted just because they describe the same event. A small time mismatch can noticeably move the Moon.

The router requires a host-resolved TT Julian Day for coverage checks. The drift validator checks returned time declarations before treating differences as regression evidence.

Geocentric and topocentric

Geocentric positions use Earth’s centre as the observer origin. Topocentric positions use a specific place on Earth’s surface, so latitude, longitude and elevation can affect the answer. This is separate from tropical versus sidereal: origin says where we observe from; zodiac says where longitude zero lies. Horizons topocentric calls also transmit that location to NASA.

Ecliptic and ecliptic longitude

The plane of Earth’s orbit — the circle the Sun appears to trace in a year. Ecliptic longitude is the angle along it: the number astrology calls a planet’s “position” (Sun at 5° Aries). Signs, houses, nakshatras and aspects all derive from it.

Celestial equator, right ascension, declination

Earth’s equator projected onto the sky. Right ascension (RA) and declination (dec) are its coordinates — sky longitude and latitude. Declination drives parallel aspects and the rising/setting math in house systems; RA is what star catalogues store.

Obliquity of the ecliptic

The ~23.44° tilt between the ecliptic and the celestial equator, needed to convert between ecliptic and equatorial coordinates. It changes slowly.

Geocentric vs heliocentric

Geocentric positions are measured from Earth’s centre, as astrology uses; heliocentric positions from the Sun, as astronomy and some research techniques do.

Retrograde and station

A planet is retrograde when its apparent geocentric longitude decreases — an illusion of relative orbital speed, not reverse motion. A station is the turn retrograde or direct; stations are slow, so their degree carries weight. Retrograde is a display flag; stations are searchable events (see Planetary stations).

Sidereal time and the local frame

The sky’s rotation angle at a location. With latitude it fixes the local horizon and meridian, and so the Ascendant and Midheaven.

Data shape — birth data

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.app/schemas/birth-data.json",
  "title": "BirthData",
  "type": "object",
  "required": ["instant", "location"],
  "properties": {
    "instant": { "type": "string", "format": "date-time", "description": "UTC" },
    "localTime": { "type": "string", "description": "Wall clock as entered" },
    "tz": { "type": "string", "description": "IANA zone, e.g. Asia/Kolkata" },
    "location": { "$ref": "#/$defs/GeoPoint" },
    "julianDay": { "type": "number", "description": "Derived, UT-based" },
    "uncertaintyMinutes": { "type": "integer", "minimum": 0, "default": 0 }
  },
  "$defs": {
    "GeoPoint": {
      "type": "object",
      "required": ["lat", "lon"],
      "properties": {
        "lat": { "type": "number", "minimum": -90, "maximum": 90 },
        "lon": { "type": "number", "minimum": -180, "maximum": 180 },
        "elevationM": { "type": "number", "default": 0 },
        "placeName": { "type": "string" }
      }
    }
  }
}

Layer 1 — The zodiac and the ayanamsa

Zodiac

A 360° band split into twelve 30° signs. It is a measuring convention laid over the ecliptic, not a physical object.

Tropical zodiac

The zodiac whose 0° Aries is fixed to the vernal equinox, where the Sun crosses the celestial equator in March. It is the default in Western astrology and in almost every consumer app.

Sidereal zodiac

The zodiac whose 0° Aries is fixed to a star reference — classically Spica/Chitra — not the equinox. Because the equinox drifts, the two zodiacs diverge by the ayanamsa.

Precession

Earth’s axis wobbles once every ~25,772 years, moving the equinox ~50.3 arc-seconds per year against the stars. That drift separates the tropical and sidereal zero points over time.

Ayanamsa

The angular difference between the tropical and sidereal zero points at a given date — roughly 24° in the 2020s and growing ~50.3″ per year. Conversion:

sidereal longitude = tropical longitude − ayanamsa   (mod 360°)

No ayanamsa is “correct”; the choice is doctrinal, so the app must store it with the chart.

The same planet can be 5° Aries tropically and 11° Pisces sidereally. A chart stored without its ayanamsa cannot be reproduced.

Rashi

The Vedic term for a 30° sign. Rashi chart (D1) means the birth chart in signs.

Data shape — zodiac configuration

{
  "$id": "https://example.app/schemas/zodiac.json",
  "title": "ZodiacConfig",
  "type": "object",
  "required": ["mode"],
  "properties": {
    "mode": { "enum": ["tropical", "sidereal"] },
    "ayanamsa": {
      "type": "object",
      "required": ["id", "degrees"],
      "properties": {
        "id": {
          "enum": ["lahiri", "raman", "krishnamurti", "fagan_bradley",
                   "yukteshwar", "true_chitra", "custom"]
        },
        "degrees": { "type": "number", "minimum": 0, "maximum": 30 },
        "computedAt": { "type": "string", "format": "date-time" }
      }
    }
  },
  "allOf": [
    {
      "if": { "properties": { "mode": { "const": "sidereal" } } },
      "then": { "required": ["ayanamsa"] }
    }
  ]
}

Layer 2 — Signs, houses and angles

Sign

One of twelve 30° zodiac sectors, each with an element (fire, earth, air, water) and a modality (cardinal, fixed, mutable). A sign is a longitude range, not a constellation.

House

One of twelve divisions of the local sky at a given time and place. Houses are tied to the horizon, so two people born at the same moment in different cities share signs but not houses.

House cusp

The boundary degree where a house begins. The 1st cusp is the Ascendant; the 10th is usually the Midheaven. A planet between cusps belongs to the house whose cusp precedes it.

The angles

House systems

Different rules for slicing the local sky. All agree on the ASC and MC but place intermediate cusps differently, so a planet can be in house 3 in one system and house 4 in another.

Store the system with the chart: “planet in the 7th” is meaningless without its house frame. Placidus, Whole Sign and Equal cover most users; the rest is professional differentiation.

Bhava and Bhava Chalit

In Jyotish, bhava means house. Bhava Chalit re-assigns planets from sign-based (rashi) houses to cusp-based houses, exposing planets that change house when the two frames disagree.

Data shape — house frame

{
  "$id": "https://example.app/schemas/house-frame.json",
  "title": "HouseFrame",
  "type": "object",
  "required": ["system", "cusps", "angles"],
  "properties": {
    "system": {
      "enum": ["placidus", "whole_sign", "equal", "koch", "porphyry",
               "regiomontanus", "campanus", "meridian", "morinus",
               "alcabitius", "polich_page", "krishnamurti", "gauquelin",
               "azimuthal", "pullen_sd"]
    },
    "cusps": {
      "type": "array", "minItems": 12, "maxItems": 12,
      "items": { "type": "number", "minimum": 0, "exclusiveMaximum": 360 },
      "description": "Index 0 = 1st house cusp"
    },
    "angles": {
      "type": "object",
      "required": ["asc", "mc"],
      "properties": {
        "asc": { "type": "number" },
        "mc":  { "type": "number" },
        "dsc": { "type": "number" },
        "ic":  { "type": "number" }
      }
    }
  }
}

Layer 3 — Bodies

A chart is a set of bodies with positions, speeds and flags. “Planet” is shorthand; the catalogue runs from the Sun to hypothetical points.

The classical seven

Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn — the only bodies in traditional Western and Vedic astrology, and the only ones with full dignity and dasha rulership.

The modern outer planets

Uranus, Neptune, Pluto — all discovered after 1781, so modern Western astrology uses them while classical astrology and mainstream Jyotish do not.

Lunar nodes — Rahu and Ketu

Where the Moon’s orbit crosses the ecliptic: Rahu north/ascending, Ketu south/descending. The mean node is a smooth average; the true node adds short-period wobble. The pair sits 180° apart and is retrograde on average.

Lilith (Black Moon)

The lunar apogee — the Moon’s farthest orbital point. Mean Lilith is smoothed, true Lilith oscillates; a calculated point, not a body.

Apogee and perigee

The farthest (apogee) and nearest (perigee) orbital points. The matrix tracks the lunar pair for distance-based techniques.

Chiron and the centaurs

Chiron, a centaur between Saturn and Uranus, is the most-used minor body after the asteroids. Pholus is a second centaur, occasionally supported; modern Western astrology interprets both.

The asteroids

The “big four” — Ceres, Pallas, Juno, Vesta — plus others such as Hygeia and Astraea. Swiss Ephemeris numbers them (SE_AST_OFFSET + number), so professional software offers 180+.

Trans-Neptunian objects (TNOs)

Bodies beyond Neptune: Eris, Sedna, Gonggong, Quaoar, Orcus. Their presence in a mobile app signals a modern, research-leaning product.

Fixed stars

Fixed reference stars, catalogued by magnitude (brightness) and used in paran, star-based and traditional work. The matrix lists them as professional-desktop-only.

Planetary moons and centre-of-body (COB)

Moons of Mars through Pluto, addressed as SE_PLMOON_OFFSET + planet*100 + moon, plus each planet’s centre of body. Research-grade: only recent Swiss Ephemeris versions expose them.

Uranian planets (hypothetical)

Eight fictitious Uranian/Hamburg points: Cupido, Hades, Zeus, Kronos, Apollon, Admetos, Vulkanus, Poseidon. They are sensitive points, not bodies.

Fictitious and disputed bodies

Isis-Transpluto, Nibiru, Harrington, Leverrier/Adams, Lowell/Pickering, Vulcan, Selena — niche points with no physical confirmation, best supported only alongside user-defined points.

Essential dignity

A classical score of how well a planet performs in a sign.

• Positive: rulership, exaltation, triplicity, term, face.
• Negative: detriment, fall.

Dignity belongs to a placement, not a body, and drives traditional interpretation.

Data shape — body position

{
  "$id": "https://example.app/schemas/body-position.json",
  "title": "BodyPosition",
  "type": "object",
  "required": ["body", "lon", "lat", "speed"],
  "properties": {
    "body": { "type": "string", "description": "Canonical id: sun, moon, mars, rahu, chiron, ceres…" },
    "lon": { "type": "number", "minimum": 0, "exclusiveMaximum": 360 },
    "lat": { "type": "number", "minimum": -90, "maximum": 90 },
    "distanceAu": { "type": "number" },
    "speed": { "type": "number", "description": "deg/day; negative = retrograde" },
    "retrograde": { "type": "boolean" },
    "stationary": { "enum": ["none", "station_retrograde", "station_direct"] },
    "sign": { "type": "string" },
    "signDegree": { "type": "number", "minimum": 0, "exclusiveMaximum": 30 },
    "house": { "type": "integer", "minimum": 1, "maximum": 12 },
    "dignity": {
      "type": "object",
      "properties": {
        "ruler": { "type": "boolean" },
        "exalted": { "type": "boolean" },
        "detriment": { "type": "boolean" },
        "fall": { "type": "boolean" }
      }
    }
  }
}

Layer 4 — Aspects

Aspect

An angular relationship between two bodies, measured as the shorter arc between their longitudes. Aspects are the grammar of a chart: they say how two placements interact.

Major aspects

Minor aspects

Orb

The tolerance around the exact angle within which an aspect counts as active. Orbs are a setting, not a fact: professional software edits them per aspect and per body. Store the orb with every aspect so two apps can reconcile their output.

Applying and separating

Applying: the faster body is moving toward exactness. Separating: it has passed. Applying aspects are traditionally stronger, and spotting either needs speeds, not just positions.

Parallel and contra-parallel

Aspects by declination instead of longitude: parallel when two bodies share declination, contra-parallel when mirrored across the equator. Rare in consumer apps, standard in traditional practice.

Aspect patterns

Named configurations of three or more aspects: T-square, Grand Trine, Grand Cross, Kite, Yod, Stellium. Computed after aspects, so they belong to the interpretation layer.

Drishti (Vedic aspects)

The Jyotish rules, which are planet-specific rather than angle-based:

Drishti counts houses and signs, not degrees, so it has no Western-style orb.

Data shape — aspect

{
  "$id": "https://example.app/schemas/aspect.json",
  "title": "Aspect",
  "type": "object",
  "required": ["from", "to", "type", "angle", "orb"],
  "properties": {
    "from": { "type": "string" },
    "to": { "type": "string" },
    "type": {
      "enum": ["conjunction", "sextile", "square", "trine", "opposition",
               "semi_sextile", "semi_square", "sesquiquadrate", "quincunx",
               "quintile", "biquintile", "parallel", "contra_parallel"]
    },
    "angle": { "type": "number", "description": "Exact angle of the aspect" },
    "exactAngle": { "type": "number", "description": "Actual separation" },
    "orb": { "type": "number", "description": "exactAngle - angle" },
    "maxOrb": { "type": "number" },
    "applying": { "type": "boolean" },
    "drishti": { "type": "boolean", "default": false },
    "pattern": { "type": ["string", "null"] }
  }
}

Layer 5 — Charts and time techniques

Natal chart

The bodies, signs, houses and angles at birth. Every other technique here compares that snapshot with another time, place or person.

Transit

Where bodies are now, compared with the natal chart. The basis of daily, weekly and monthly forecasts.

Secondary progression

The “one day = one year” technique: the sky one day after birth symbolises the first year, two days the second, and so on. The progressed Moon moves ~1° per month, the progressed Sun ~1° per year.

Solar arc

The progressed Sun’s travelled arc added to every natal point, giving one “age arc”. A simplification of progression, popular for event timing.

Tertiary and minor progression

Alternative time keys: tertiary maps one day to one lunar month, minor one lunar month to one year. Professional-tier features.

Solar return

The chart for the Sun’s return to its natal longitude, roughly each birthday; the standard yearly forecast.

Lunar return

The same idea for the Moon, roughly monthly. Lunar phase return uses the Sun–Moon phase angle instead of the Moon alone.

Planetary return

A return chart for any planet (Mars, Jupiter, Saturn…), for cycles longer or shorter than a year. Desktop-only in most products.

Synastry

Two natal charts compared, each person’s bodies aspected against the other’s, usually as a bi-wheel (tri/quad wheel for groups). The relationship view.

Composite chart

One chart built from the midpoints of two people’s longitudes. It describes the relationship as an entity rather than an interaction.

Davison chart

A relationship chart built from the midpoint in time and space of the two births, then cast as a real chart. Unlike the composite, it has real houses and angles.

Relocation chart

The natal chart re-cast for another location: houses and angles change, sign placements do not. Used for moving, travel and astrocartography.

Horary

A chart for the moment a question is asked, used to answer it. Traditional, and rare in consumer software.

Electional chart / Muhurta

The reverse of horary: a future moment chosen for favourable placements at an event such as a wedding, travel or launch. In Jyotish this is muhurta, with dedicated rules and a panchang.

Harmonic chart

Every longitude multiplied by a whole number n (H4, H5, H9…). Harmonics isolate certain symmetries; a professional/advanced feature.

Antiscia

Mirror points around the 0° Cancer–0° Capricorn axis: 10° Aries has its antiscion at 20° Virgo. They show hidden connections and are usually drawn as an extra ring.

Eclipse chart

A chart cast for a solar or lunar eclipse, globally or for a location. Eclipse search — the next eclipse and its visibility — is a desktop feature.

Astrocartography (Astro Maps)

A world map of where a planet was rising, setting, culminating or anti-culminating at birth; living on a line emphasises that planet. Geodetic and paran maps are related techniques.

Planetary stations

The dates a planet turns retrograde or direct, often searched as events because they mark turning points. Displaying them is a desktop feature.

Planetary nodes and apsides

The nodes and apsides (perihelion/aphelion) of each planet’s own orbit, not just the Moon’s. Research-grade, desktop-only.

Firdaria

A Persian time-lord system: 75 years of planetary periods with sub-periods, starting with the Sun for a day birth and the Moon for a night birth.

Zodiacal Releasing

A Hellenistic time-lord technique releasing periods from a lot — usually Spirit or Fortune — counted in years per sign. Needs a lot and a zodiac; a professional feature.

Lots / Parts

Derived points from the ASC, Sun and Moon, the best known being the Lot of Fortune (ASC + Moon − Sun by day, reversed by night). A Hellenistic speciality.

Life time arcs

One-degree-per-year arcs from the natal chart for long-range timing, related to solar arc but applied across the whole lifespan.

Data shape — chart request and chart

{
  "$id": "https://example.app/schemas/chart.json",
  "title": "ChartRequest",
  "type": "object",
  "required": ["kind", "subject", "zodiac", "houseSystem"],
  "properties": {
    "kind": {
      "enum": ["natal", "transit", "secondary_progression", "solar_arc",
               "tertiary_progression", "minor_progression", "solar_return",
               "lunar_return", "lunar_phase_return", "planetary_return",
               "synastry", "composite", "davison", "relocation",
               "horary", "electional", "harmonic", "antiscia", "eclipse"]
    },
    "subject": { "$ref": "birth-data.json" },
    "partner": { "$ref": "birth-data.json" },
    "target": { "$ref": "birth-data.json", "description": "Transit/election instant" },
    "zodiac": { "$ref": "zodiac.json" },
    "houseSystem": { "type": "string", "default": "placidus" },
    "harmonic": { "type": "integer", "minimum": 2 },
    "options": {
      "type": "object",
      "properties": {
        "bodies": { "type": "array", "items": { "type": "string" } },
        "aspects": { "type": "array", "items": { "type": "string" } },
        "orbs": { "type": "object", "additionalProperties": { "type": "number" } },
        "includeFixedStars": { "type": "boolean", "default": false }
      }
    }
  }
}

A computed chart returns the same inputs plus bodies, houses, aspects and meta (engine, ephemeris version, ayanamsa, computed-at). Keeping request and result together makes a chart reproducible.

Layer 6 — The Vedic stack

Jyotish reuses Layers 0–2 and adds finer divisions plus a time system: sign → nakshatra → pada → dasha, each step subdividing the last.

Nakshatra

One of 27 lunar mansions, each 360° / 27 = 13°20′ wide, with a ruling planet and its deities and symbols. After the rashi, the Moon’s nakshatra is Jyotish’s most-used placement.

Pada

A quarter nakshatra: 13°20′ / 4 = 3°20′. Each pada maps to a navamsa sign (D9), so the pada and the D9 chart are two views of one division.

Varga (divisional chart)

Each sign subdivided into n parts, each part mapped to a sign. D1 is the birth chart, D9 (navamsa) the marriage and dharma chart; the matrix’s full set runs to D60.

Shodashvarga is the standard set of sixteen (D1, D2, D3, D4, D7, D9, D10, D12, D16, D20, D24, D27, D30, D40, D45, D60). Some engines go further, to D144.

Dasha

Planetary time-lords: life divided into planetary periods, recursively. Sequence and lengths depend on the system and on the birth nakshatra.

The five dasha levels nest: Maha (major) → Antar (sub) → Pratyantar → Sookshma → Prana. Professional tools show all five.

Ashtakavarga

A bindu (point) scoring system: seven planets plus the Ascendant contribute points to houses and signs, giving a per-planet Ashtakavarga and a combined Sarvashtakavarga (337 bindus). More bindus mean stronger transits. Trikona and Shodashavarga variants score selected house groups and the sixteen divisional charts.

Shadbala

Six-fold planetary strength in rupas:

Bhavabala applies the same six measures to houses.

Yoga (Vedic)

A named planetary combination with a predicted effect. Families: Pancha Mahapurusha (five great-person yogas), Raja (power), Dhana (wealth), Nabhasa (sky patterns). Detection is an interpretation layer over positions.

Panchang

The five-limbed Hindu almanac for a day:

Extended panchang adds sunrise/sunset, Rahukalam (an inauspicious window) and Gulikakalam. It is location- and timezone-sensitive.

Muhurta

Electional Jyotish: a favourable window chosen from panchang, dashas, transits and lifting/obstruction rules. The matrix counts 18 life events as a typical scope. Some tools also implement the older Surya Siddhanta rules.

KP system (Krishnamurti Paddhati)

A modern Vedic school built on 249 sub-lords (nine sub-parts per nakshatra), Placidus cusps and a “ruling planets” method. Its output is more granular than classical Jyotish.

Lalkitab

A folk Vedic system, the “Red Book”, with its own house meanings and remedies. Rare in software.

Ashtakoot / Dashkoot

Marriage compatibility scoring. Ashtakoot uses eight factors worth 36 gunas (Varna, Vashya, Tara, Yoni, Graha Maitri, Gana, Bhakoot, Nadi); Dashkoot adds two more.

Data shape — Vedic outputs

{
  "$id": "https://example.app/schemas/vedic.json",
  "title": "VedicSnapshot",
  "type": "object",
  "required": ["vargas", "dashas", "panchang"],
  "properties": {
    "vargas": {
      "type": "array",
      "items": {
        "type": "object",
        "required": ["division", "sign"],
        "properties": {
          "division": { "type": "integer", "enum": [1,2,3,4,7,9,10,12,16,20,24,27,30,40,45,60] },
          "name": { "type": "string" },
          "ascSign": { "type": "string" },
          "positions": {
            "type": "array",
            "items": {
              "type": "object",
              "properties": {
                "body": { "type": "string" },
                "sign": { "type": "string" },
                "degree": { "type": "number" }
              }
            }
          }
        }
      }
    },
    "dashas": {
      "type": "object",
      "required": ["system", "tree"],
      "properties": {
        "system": { "enum": ["vimshottari", "ashtottari", "yogini", "kalachakra", "chara"] },
        "tree": { "$ref": "#/$defs/DashaNode" }
      }
    },
    "panchang": {
      "type": "object",
      "required": ["tithi", "nakshatra", "yoga", "karana", "vara"],
      "properties": {
        "tithi": { "type": "string" },
        "nakshatra": { "type": "string" },
        "yoga": { "type": "string" },
        "karana": { "type": "string" },
        "vara": { "type": "string" },
        "sunrise": { "type": "string", "format": "date-time" },
        "sunset": { "type": "string", "format": "date-time" },
        "rahukalam": { "type": "object" }
      }
    }
  },
  "$defs": {
    "DashaNode": {
      "type": "object",
      "required": ["lord", "level", "start", "end"],
      "properties": {
        "lord": { "type": "string" },
        "level": { "enum": ["maha", "antar", "pratyantar", "sookshma", "prana"] },
        "start": { "type": "string", "format": "date-time" },
        "end": { "type": "string", "format": "date-time" },
        "children": { "type": "array", "items": { "$ref": "#/$defs/DashaNode" } }
      }
    }
  }
}

Layer 7 — Delivery and rendering

Calculation is only half the product. This layer is what the user sees and what developers integrate with.

Ephemeris engine

The library that computes positions. Swiss Ephemeris is AGPL or CHF 700 commercial, NASA JPL DE440 can be used directly, XALEN is Apache-2.0, Roxy Ephemeris MIT — a licence decision, not just a technical one.

Chart wheel

The circular drawing: sign ring outside, house cusps, planet glyphs and degrees, aspect lines in the middle. Wheel styles vary ring order, glyph set and aspect-line treatment.

Wheel editor

User control of colours, line weights, glyphs, ring layout and house numbering. A professional-desktop differentiator mobile apps usually omit.

Dynamic lists

Generated tables of aspects, transits or progressions for a period, usually exportable. Once desktop-only, now returned by APIs as JSON.

Graphical ephemeris

A plot of planetary longitudes over time, for spotting stations, ingresses and patterns visually. Desktop-only today.

Astro sheets

Tabular displays — positions, house tables, midpoint lists — for quick reading or printing.

Animator / chart stepper

A control that advances the chart through time so transits can be watched. Desktop animates smoothly; mobile usually steps discretely.

REST / JSON API

The integration surface: request a chart, receive positions, houses, aspects and interpretations as JSON. Modern providers add MCP servers so LLM agents can call the same calculations as tools.

Render formats

• SVG — scalable, editable, best for web.
• PNG — raster, social sharing.
• PDF — print, reports.

Server-side chart images are usually SVG or PNG; report exports are PDF.

Cloud sync

Chart storage across devices — iCloud in AstroGold’s case. Calculation APIs are stateless, so sync belongs to the app, not the engine.

Data shape — render options

{
  "$id": "https://example.app/schemas/render.json",
  "title": "RenderOptions",
  "type": "object",
  "properties": {
    "format": { "enum": ["svg", "png", "pdf"], "default": "svg" },
    "wheelStyle": { "enum": ["western", "vedic_north", "vedic_south", "grid"] },
    "sizePx": { "type": "integer", "minimum": 200, "maximum": 4000, "default": 800 },
    "theme": { "enum": ["light", "dark", "print"], "default": "light" },
    "show": {
      "type": "object",
      "properties": {
        "signs": { "type": "boolean", "default": true },
        "houses": { "type": "boolean", "default": true },
        "degrees": { "type": "boolean", "default": true },
        "aspects": { "type": "boolean", "default": true },
        "minorAspects": { "type": "boolean", "default": false },
        "fixedStars": { "type": "boolean", "default": false }
      }
    },
    "language": { "type": "string", "default": "en" }
  }
}

The canonical payload

The layers compose into one object. Standardise this shape first: every feature above is a projection of it.

{
  "meta": {
    "engine": "swiss-ephemeris",
    "engineVersion": "2.10.03",
    "computedAt": "2026-10-24T08:00:00Z"
  },
  "request": {
    "kind": "natal",
    "subject": {
      "instant": "1994-08-17T04:35:00Z",
      "tz": "Asia/Kolkata",
      "location": { "lat": 22.5726, "lon": 88.3639, "placeName": "Kolkata" }
    },
    "zodiac": {
      "mode": "sidereal",
      "ayanamsa": { "id": "lahiri", "degrees": 23.86 }
    },
    "houseSystem": "whole_sign"
  },
  "houses": {
    "system": "whole_sign",
    "cusps": [150.0, 180.0, 210.0, 240.0, 270.0, 300.0,
              330.0, 0.0, 30.0, 60.0, 90.0, 120.0],
    "angles": { "asc": 150.0, "mc": 60.0 }
  },
  "bodies": [
    {
      "body": "sun", "lon": 133.42, "lat": 0.0, "speed": 0.96,
      "retrograde": false, "sign": "leo", "signDegree": 13.42, "house": 12
    },
    {
      "body": "moon", "lon": 13.33, "lat": 4.1, "speed": 13.2,
      "retrograde": false, "sign": "aries", "signDegree": 13.33, "house": 8
    }
  ],
  "aspects": [
    {
      "from": "sun", "to": "moon", "type": "trine",
      "angle": 120, "exactAngle": 120.09, "orb": 0.09,
      "maxOrb": 8, "applying": false
    }
  ],
  "vedic": {
    "vargas": [{ "division": 1, "name": "rasi", "ascSign": "virgo" }],
    "dashas": {
      "system": "vimshottari",
      "tree": {
        "lord": "venus", "level": "maha",
        "start": "1994-08-17T00:00:00Z", "end": "2014-08-17T00:00:00Z"
      }
    },
    "panchang": {
      "tithi": "shukla ekadashi",
      "nakshatra": "bharani",
      "yoga": "vishkambha",
      "karana": "vanija",
      "vara": "wednesday"
    }
  }
}

Glossary A–Z

Sources

• Feature matrix — the term inventory this glossary expands.
• Competitive report — market context for each capability tier.
• Swiss Ephemeris Programmer’s Manual — bodies, houses, ayanamsa, fixed stars, sidereal mode.
• AstroGold comparison table — the desktop/mobile/API feature split.

Research notes compiled October 2026. Definitions are tradition-neutral where traditions differ; the ayanamsa, house system and node type are always inputs, never assumptions.