Western Solar Arc
asterwise_get_western_solar_arc
Western Solar Arc Directions for a target date: the solar arc (progressed Sun minus natal Sun) is added to every natal planet and angle. It is approximately 1° per year; unlike secondary progressions, all planets advance at the same rate.
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
birth | object | yes | Birth data for Western astrology tools (tropical zodiac). Required fields: date, time, lat, lon. Optional fields: person_name, timezone, house_system. |
response_format | enum: markdown, json | no | Output format: 'markdown' (default) for a readable report, or 'json' for the raw structured payload. |
target_date | string/null | no | Date to direct the chart to, YYYY-MM-DD. Defaults to today (UTC). |
What it covers
Solar arc directions — one delta longitude applied to every natal body and the angles. Classic predictive technique for timing outer events.
Workflow
BEFORE: asterwise_get_western_natal.
AFTER: None.
Input
birth — WesternBirthData.
target_date (optional YYYY-MM-DD) — defaults to today.
Output contract
data.target_date, data.solar_arc, data.age_years
data.natal_sun_longitude, data.progressed_sun_longitude
data.directed_planets[] — 10 objects: name, natal_longitude, directed_longitude, sign, degree_in_sign, dignity, dignity_score, dignity_disputed
data.directed_ascendant, data.directed_ascendant_sign
data.directed_mc, data.directed_mc_sign
Response format
response_format=json serialises the complete response as indented JSON.
response_format=markdown renders the same data as a human-readable report.
Both modes return identical underlying data.
Compute class
MEDIUM_COMPUTE (~400ms)
Errors
INVALID_PARAMS (local): WesternBirthData validation failures.
INTERNAL_ERROR: Any upstream API failure or timeout → MCP INTERNAL_ERROR
Edge cases:
All planets advance at the same rate (solar arc ≈ 1°/year). This is Solar Arc Directions — different from secondary progressions where each planet moves at its own astronomical speed.
Do not confuse with
asterwise_get_western_secondary_progressions — each planet moves at its own rate.
asterwise_get_western_transits_daily — real-time transits, not arc directions.
Connect
Remote MCP endpoint: https://mcp.asterwise.com/mcp. Authenticate with Authorization: Bearer <API key> or OAuth. See the MCP setup guide.